I found it easier to use the offsets in the Properties panel to move the two ends of the l.v. ties.
My recollection of how to adapt the playback was to extend the audio in the Key Editor to the total length of the held note (hoping it is the same in both endings) and then suppressing playback of the tied-to notes. Make sure the tied note and tied-to notes are in different voices.
This was some time ago, so I hope if I have missed any of the subtleties, someone with more recent experience can correct me.
repeatEndingSustains.dorico (503.7 KB)