Need with help missing sign-offs for PR

[Qubitium]

We have a pending PR for merge: https://github.com/vllm-project/vllm/pull/7086/commits.

The PR was create before the time vLLM required sign-offs. Now it it does. The PR branch has 2 different committers where both committers have missing sign-offs.

I have tried:

git rebase HEAD~50 --signoff 

And similar fixes but the rebase cause a file to have a conflict (how is this even possible?) and conflict diffs are non-sensical since it's for a commit very early in the history of the branch and I have lost all memory and can't make head or tales about the strange conflict diffs.

Is there a way to just amend "missing" sign-offs in a branch?

This is driving me nuts. Thanks for any help or pointers.