diff --git a/Library/Homebrew/dev-cmd/pr-upload.rb b/Library/Homebrew/dev-cmd/pr-upload.rb
index 4217f27e08..ab2141aafb 100644
--- a/Library/Homebrew/dev-cmd/pr-upload.rb
+++ b/Library/Homebrew/dev-cmd/pr-upload.rb
@@ -16,7 +16,8 @@ module Homebrew
         EOS
         switch "--keep-old",
                description: "If the formula specifies a rebuild version, " \
-                            "attempt to preserve its value in the generated DSL."
+                            "attempt to preserve its value in the generated DSL. " \
+                            "When using GitHub Packages, this also appends the manifest to the existing list."
         switch "-n", "--dry-run",
                description: "Print what would be done rather than doing it."
         switch "--no-commit",
@@ -34,7 +35,6 @@ module Homebrew
                description: "Use the specified download strategy class for downloading the bottle's URL instead of " \
                             "Homebrew's default."
 
-        conflicts "--upload-only", "--keep-old"
         conflicts "--upload-only", "--no-commit"
 
         named_args :none
diff --git a/completions/fish/brew.fish b/completions/fish/brew.fish
index dcae08cec4..d6ddc4fc7b 100644
--- a/completions/fish/brew.fish
+++ b/completions/fish/brew.fish
@@ -1282,7 +1282,7 @@ __fish_brew_complete_arg 'pr-upload' -l committer -d 'Specify a committer name a
 __fish_brew_complete_arg 'pr-upload' -l debug -d 'Display any debugging information'
 __fish_brew_complete_arg 'pr-upload' -l dry-run -d 'Print what would be done rather than doing it'
 __fish_brew_complete_arg 'pr-upload' -l help -d 'Show this message'
-__fish_brew_complete_arg 'pr-upload' -l keep-old -d 'If the formula specifies a rebuild version, attempt to preserve its value in the generated DSL'
+__fish_brew_complete_arg 'pr-upload' -l keep-old -d 'If the formula specifies a rebuild version, attempt to preserve its value in the generated DSL. When using GitHub Packages, this also appends the manifest to the existing list'
 __fish_brew_complete_arg 'pr-upload' -l no-commit -d 'Do not generate a new commit before uploading'
 __fish_brew_complete_arg 'pr-upload' -l quiet -d 'Make some output more quiet'
 __fish_brew_complete_arg 'pr-upload' -l root-url -d 'Use the specified URL as the root of the bottle\'s URL instead of Homebrew\'s default'
diff --git a/completions/zsh/_brew b/completions/zsh/_brew
index f78bc3d240..95997969f4 100644
--- a/completions/zsh/_brew
+++ b/completions/zsh/_brew
@@ -1591,12 +1591,12 @@ _brew_pr_upload() {
     '--debug[Display any debugging information]' \
     '--dry-run[Print what would be done rather than doing it]' \
     '--help[Show this message]' \
-    '(--upload-only)--keep-old[If the formula specifies a rebuild version, attempt to preserve its value in the generated DSL]' \
+    '--keep-old[If the formula specifies a rebuild version, attempt to preserve its value in the generated DSL. When using GitHub Packages, this also appends the manifest to the existing list]' \
     '(--upload-only)--no-commit[Do not generate a new commit before uploading]' \
     '--quiet[Make some output more quiet]' \
     '--root-url[Use the specified URL as the root of the bottle'\''s URL instead of Homebrew'\''s default]' \
     '--root-url-using[Use the specified download strategy class for downloading the bottle'\''s URL instead of Homebrew'\''s default]' \
-    '(--keep-old --no-commit)--upload-only[Skip running `brew bottle` before uploading]' \
+    '(--no-commit)--upload-only[Skip running `brew bottle` before uploading]' \
     '--verbose[Make some output more verbose]' \
     '--warn-on-upload-failure[Warn instead of raising an error if the bottle upload fails. Useful for repairing bottle uploads that previously failed]'
 }
diff --git a/docs/Manpage.md b/docs/Manpage.md
index a3e426d77a..ccae064d6c 100644
--- a/docs/Manpage.md
+++ b/docs/Manpage.md
@@ -2563,7 +2563,8 @@ Apply the bottle commit and publish bottles to a host.
 `--keep-old`
 
 : If the formula specifies a rebuild version, attempt to preserve its value in
-  the generated DSL.
+  the generated DSL. When using GitHub Packages, this also appends the manifest
+  to the existing list.
 
 `-n`, `--dry-run`
 
diff --git a/manpages/brew.1 b/manpages/brew.1
index 82a4fffa7d..e20988d544 100644
--- a/manpages/brew.1
+++ b/manpages/brew.1
@@ -1634,7 +1634,7 @@ Comma\-separated list of workflows which can be ignored if they have not been ru
 Apply the bottle commit and publish bottles to a host\.
 .TP
 \fB\-\-keep\-old\fP
-If the formula specifies a rebuild version, attempt to preserve its value in the generated DSL\.
+If the formula specifies a rebuild version, attempt to preserve its value in the generated DSL\. When using GitHub Packages, this also appends the manifest to the existing list\.
 .TP
 \fB\-n\fP, \fB\-\-dry\-run\fP
 Print what would be done rather than doing it\.