diff --git a/doc/NEWS b/doc/NEWS
index a6fda198c55..764331fe031 100644
--- a/doc/NEWS
+++ b/doc/NEWS
@@ -210,7 +210,9 @@ Major changes from 1.9.0-jumbo-1 (May 2019) in this bleeding-edge version:
 
 - Add new option --catch-up=NAME, for running a new session only until it
   reaches the candidates tried count of a different, existing and paused
-  session, then exit.  [magnum; 2021]
+  session, then exit.  Unless the --no-catch-up-add option is also given,
+  the new input hashes (file names) used for the new session will be added
+  to the old session file once caught up.  [magnum; 2021, 2026]
 
 - Add BestCrypt Volume Encryption V4 format.  [Jean-Christophe Delaunay; 2021]
 
diff --git a/doc/OPTIONS b/doc/OPTIONS
index 7d99087ee88..2a7803efa59 100644
--- a/doc/OPTIONS
+++ b/doc/OPTIONS
@@ -229,9 +229,11 @@ numbers printed on the status line mean?"
 Limit the session to running only until it reaches the candidates tried
 count of a different, existing and paused session NAME.  This can be
 used for adding more hashes to an existing job:  After the new session
-finishes, just concatenate the new hashes to the older session's hash
-file and resume the old session.  This will end up more or less as if
-both sets of hashes were in the original session to start with.
+finishes, the new hashes (file names) will be added to the older session
+file so you can just resume that session.  This will end up just as if both
+sets of hashes were in the original session to start with, with no wasted
+resources or time (assuming salted hashes).  If you do not wish the original
+session file to be touched, also add the --no-catch-up-add option.
 
 --make-charset=FILE		make a charset, overwriting FILE
 
diff --git a/src/john.c b/src/john.c
index 6429867c3fd..27a5cf37495 100644
--- a/src/john.c
+++ b/src/john.c
@@ -1,7 +1,7 @@
 /*
  * This file is part of John the Ripper password cracker,
  * Copyright (c) 1996-2024 by Solar Designer
- * Copyright (c) 2009-2025, magnum
+ * Copyright (c) 2009-2026, magnum
  * Copyright (c) 2021, Claudio
  * Copyright (c) 2009-2018, JimF
  *
@@ -1954,10 +1954,14 @@ static void john_done(void)
 				        mask_iter_warn);
 		}
 		if (event_abort && options.catchup && john_max_cands && status.cands >= john_max_cands) {
+			if (options.catchup_add)
+				rec_add_files(options.catchup);
 			event_abort = 0;
-			log_event("Done catching up with '%s'", options.catchup);
+			log_event("Done catching up with '%s'%s", options.catchup,
+			          options.catchup_add ? ", and added this session's password file(s) to it" : "");
 			if (john_main_process)
-				fprintf(stderr, "Done catching up with '%s'\n", options.catchup);
+				fprintf(stderr, "Done catching up with '%s'%s\n", options.catchup,
+				        options.catchup_add ? ", and added this session's password file(s) to it" : "");
 		}
 		if (event_abort) {
 			char *abort_msg = (aborted_by_timer) ?
diff --git a/src/options.c b/src/options.c
index 70cba0a9270..ae65c7d418b 100644
--- a/src/options.c
+++ b/src/options.c
@@ -1,8 +1,8 @@
 /*
  * This file is part of John the Ripper password cracker,
  * Copyright (c) 1996-2025 by Solar Designer
- *
- * ...with changes in the jumbo patch, by JimF and magnum (and various others?)
+ * Copyright (c) 2009-2026, magnum
+ * Copyright (c) 2009-2018, JimF
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted.
@@ -139,6 +139,7 @@ static struct opt_entry opt_list[] = {
 	{"restore", FLG_RESTORE_SET, FLG_RESTORE_CHK, 0, ~FLG_RESTORE_SET & ~GETOPT_FLAGS, OPT_FMT_STR_ALLOC, &options.session},
 	{"session", FLG_SESSION, FLG_SESSION, FLG_CRACKING_SUP, OPT_REQ_PARAM, OPT_FMT_STR_ALLOC, &options.session},
 	{"catch-up", FLG_ONCE, 0, 0, OPT_REQ_PARAM, OPT_FMT_STR_ALLOC, &options.catchup},
+	{"catch-up-add", FLG_ONCE, 0, 0, USUAL_REQ_CLR | OPT_TRISTATE, NULL, &options.catchup_add},
 	{"status", FLG_STATUS_SET, FLG_STATUS_CHK, 0, ~FLG_STATUS_SET & ~GETOPT_FLAGS, OPT_FMT_STR_ALLOC, &options.session},
 	{"make-charset", FLG_MAKECHR_SET, FLG_MAKECHR_CHK, 0, FLG_CRACKING_CHK | FLG_SESSION | OPT_REQ_PARAM, OPT_FMT_STR_ALLOC, &options.charset},
 	{"show", FLG_SHOW_SET, FLG_SHOW_CHK, 0, FLG_CRACKING_SUP | FLG_MAKECHR_CHK, OPT_FMT_STR_ALLOC, &show_uncracked_str},
@@ -332,6 +333,8 @@ JOHN_USAGE_FORK \
 "--no-log                   Disables creation and writing to john.log file\n"  \
 "--bare-always-valid=Y      Treat bare hashes as valid (Y/N)\n" \
 "--catch-up=NAME            Catch up with existing (paused) session NAME\n" \
+"--no-catch-up-add          Do not add the new hashes (files) to NAME after\n" \
+"                           --catch-up=NAME caught up\n" \
 "--config=FILE              Use FILE instead of john.conf or john.ini\n" \
 "--encoding=NAME            Input encoding (eg. UTF-8, ISO-8859-1). See also\n" \
 "                           doc/ENCODINGS.\n" \
@@ -623,6 +626,10 @@ void opt_init(char *name, int argc, char **argv)
 	if (options.catchup && options.max_cands)
 		error_msg("Can't combine --max-candidates and --catch-up options\n");
 
+	if ((options.catchup_add != -1) && !options.catchup)
+		error_msg("The --%scatch-up-add option can only be used with --catch-up\n",
+		          options.catchup_add ? "" : "no-");
+
 	if (options.flags & FLG_STATUS_CHK) {
 #if OS_FORK
 		char *rec_name_orig = rec_name;
diff --git a/src/options.h b/src/options.h
index 09d82605e49..f0b620e3987 100644
--- a/src/options.h
+++ b/src/options.h
@@ -1,8 +1,8 @@
 /*
  * This file is part of John the Ripper password cracker,
  * Copyright (c) 1996-98,2003,2006,2013 by Solar Designer
- *
- * ...with changes in the jumbo patch, by JimF and magnum (and various others?)
+ * Copyright (c) 2009-2026, magnum
+ * Copyright (c) 2009-2015, JimF
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted.
@@ -457,6 +457,8 @@ struct options_main {
 	int crack_status;
 /* --catch-up=oldsession */
 	char *catchup;
+/* --catch-up-add (tri-state) */
+	int catchup_add;
 #if defined(HAVE_OPENCL) || defined(HAVE_ZTEX)
 /* --mask-internal-target=N */
 	int req_int_cand_target;
diff --git a/src/recovery.c b/src/recovery.c
index e7048dffece..e46f343b5c7 100644
--- a/src/recovery.c
+++ b/src/recovery.c
@@ -1,8 +1,8 @@
 /*
  * This file is part of John the Ripper password cracker,
  * Copyright (c) 1996-2003,2005,2006,2009,2010,2013,2017 by Solar Designer
- *
- * ...with changes in the jumbo patch, by JimF and magnum.
+ * Copyright (c) 2009-2026, magnum
+ * Copyright (c) 2009-2018, JimF
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted.
@@ -763,3 +763,82 @@ uint64_t rec_read_cands(char *session)
 
 	return ret;
 }
+
+void rec_add_files(char *session)
+{
+	char *catchup_name;
+	FILE *catchup_file;
+	int64_t catchup_size = 0;
+	char suffix[1 + 20 + sizeof(RECOVERY_SUFFIX)];
+	const char *sfx = RECOVERY_SUFFIX;
+
+	if (!john_main_process && options.node_min) {
+		snprintf(suffix, sizeof(suffix), ".%u%s", options.node_min, RECOVERY_SUFFIX);
+		sfx = suffix;
+	}
+	catchup_name = path_session(session, sfx);
+
+	if (!(catchup_file = fopen(catchup_name, "r+")))
+		pexit("fopen catch-up file: '%s'", catchup_name);
+
+#if !(__MINGW32__ || _MSC_VER)
+	if (jtr_lock(fileno(catchup_file), F_SETLK, F_WRLCK, catchup_name))
+		error_msg("Error: Catch-up session-file '%s' is locked\n", catchup_name);
+#endif
+
+	/* Check the original session-file's size */
+	if (jtr_fseek64(catchup_file, 0, SEEK_END))
+		pexit("fseek");
+	if ((catchup_size = jtr_ftell64(catchup_file)) == -1)
+		pexit("ftell");
+	if (jtr_fseek64(catchup_file, 0, SEEK_SET))
+		pexit("fseek");
+	if (catchup_size <= 0 || catchup_size > SIZE_MAX)
+		error_msg("Error: %s invalid size", catchup_name);
+
+	/* Read original session-file data into memory */
+	char *catchup_data = mem_alloc_tiny(catchup_size + 1, MEM_ALIGN_NONE);
+	catchup_data[catchup_size] = '\0';
+
+	if (fread(catchup_data, 1, (size_t)catchup_size, catchup_file) != catchup_size) {
+		if (ferror(catchup_file))
+			pexit("fread");
+		error_msg("Error: fread: Unexpected EOF in %s\n", rec_name);
+	}
+
+	/* Parse session header */
+	char magic[16];
+	int argc, offset;
+	if (sscanf(catchup_data, "%15s\n%d\n%n", magic, &argc, &offset) != 2 || argc < 2)
+		error_msg("Error: %s invalid session-file format\n", rec_name);
+
+	if (offset > catchup_size)
+		error_msg("Error: %s corrupt offset\n", rec_name);
+
+	if (jtr_fseek64(catchup_file, 0, SEEK_SET))
+		pexit("fseek");
+
+	/* Rewrite header */
+	fprintf(catchup_file, "%s\n%d\n", magic, argc + (int)options.passwd->count);
+
+	/* Append new file entries */
+	struct list_entry *current;
+	for (current = options.passwd->head; current; current = current->next)
+		fprintf(catchup_file, "%s\n", current->data);
+
+	/* Append original tail */
+	fprintf(catchup_file, "%s", catchup_data + offset);
+	fclose(catchup_file);
+
+	/* Delete this session's file */
+	const char *full_rec_name = path_expand(rec_name);
+	if (unlink(full_rec_name))
+		pexit("unlink: %s", full_rec_name);
+
+	/* Close this session's file */
+	if (rec_file) {
+		if (fclose(rec_file))
+			pexit("fclose");
+		rec_file = NULL;
+	}
+}
diff --git a/src/recovery.h b/src/recovery.h
index ac431f17df0..f6582c23fb5 100644
--- a/src/recovery.h
+++ b/src/recovery.h
@@ -118,4 +118,10 @@ extern void rec_restore_mode(int (*restore_mode)(FILE *file));
  */
 extern uint64_t rec_read_cands(char *session);
 
+/*
+ * Add the current session's password files to the file we caught up with.
+ * --catch-up=SESSION does this after successfully catching up.
+ */
+extern void rec_add_files(char *session);
+
 #endif