I think the things that sealed the deal for us in Dublin were:
-my offer letter confirming my internal transfer with my company I.e. an offer for a U.S. role. as the petitoner
-One way plane tickets
-Paid movers deposits
-Deposit paid to my daughter’s new daycare
Unfortunately, it seems Dublin is being quite picky on the domicile stuff these days and folks are having to make actual financial commitments to satisfy the requirements, if they aren’t willing/able to go ahead of the spouse back to the U.S. That is, of course, also an option although I realize it’s less than ideal.
I’m not sure if this site has a private message function but if so, please feel free to reach out if you want to chat more about this.