Hi, thanks. I think that's what happened the first time I mentioned, when a person and the rest of their line disappeared. Luckily it was all still attached to another relative.
There wasn't much history or any sources to lose on the one last night. So I wrote down the info and went for it. Luckily it was fine and everything is still looking good this morning. I'm wondering if it may happen again as I'm moving through the tree because of the Multi relationship, like you said. If it does I'll just have to check my a-z list again for any duplicates and if there are none, just put up with the confusion. Don't want to lose any sources.
Thanks for your advise.