I think you have two options. One is to get a necropsy when the next one dies. That way you have a much better chance of knowing what you are dealing with. It could be many different things. A necropsy won't necessarily give you the answer but it might.
There are different kinds of Marek's. Usually Marek's doesn't totally wipe out your flock. It's possible the type of Marek's your chickens have, if it is Marek's, are damaging them internally so when they get extra stress from other factors they can't handle it.
The other option is to commit to not taking any with you on the move. I'd also question taking any chicken equipment like coo[s, brooders, feeders or waterers, though a good sterilization might suffice. A clean start may be all you need.
It's not always an easy decision.
There are different kinds of Marek's. Usually Marek's doesn't totally wipe out your flock. It's possible the type of Marek's your chickens have, if it is Marek's, are damaging them internally so when they get extra stress from other factors they can't handle it.
The other option is to commit to not taking any with you on the move. I'd also question taking any chicken equipment like coo[s, brooders, feeders or waterers, though a good sterilization might suffice. A clean start may be all you need.
It's not always an easy decision.