How to selectively remove files from Back in Time snapshots

I use Back in Time for my backups, and I have set it to backup my entire Home directory.

Inside it there is a directory (VirtualMachines) where I store a couple of virtual machines, that occupy a lot of space and doesn’t really need to be preserved as often and with that many copies of the other, more important files.

I have modified my Back in Time configuration and removed this directory from the backup schedule, but the relevant files are still present on all the old snapshots; I’d like to remove them, to free some space on the hard disk where they are stored (we are talking about a 20GB file for every modified state of any given VM), but I can’t find how to do it from the program interface.

I’m wondering if it is safe (i.e. it won’t corrupt or break the whole snapshot) to manually remove those files from the snapshots storage.

backintime uses rsync so it should be no problem to simply delete the files

I have experimented by deleting those files from an older snapshot, and it seems that everything else works fine.

rsync is just a fancy copy program it does not rely on any metadata so it just copies files from one place to another if the files are newer.