I know you don't have to be legally married in Mexico to use the chapel at EDR for your wedding. We had a symbolic ceremony, and the chapel was our back up location in case of bad weather. EDR never asked us when we did our legal marriage - so it could have been done before or after we were married at EDR.
I think you may be asking about a Catholic ceremony + the legal/civil ceremony?
Here's the skinny on MX ceremonies available through Lomas:
Civil: legal in MX, must file paperwork in US to be legal here, this has a set script, and require you to be there 3 business days before your wedding, do the paperwork and have blood tests.
Catholic: The Catholic ceremony has to be held in the chapel/church I believe. Also requires additional paperwork from the Catholic church. It isn't a legal ceremony, but can be combined with the above civil/legal ceremony based on Lomas' website. So you could also choose to do the legal portion at home.
Symbolic: not legal in MX, not legal in US - you'd have to do your legal marriage in US; you can use the civil script, or write your own. No blood tests required, no 3 day business day requirement. Many brides choose this route, and do the legal marriage/paperwork at home (this is what we did.)
Here's a link to Lomas' requirements with the various ceremonies:
So if I wanted to get married in the chapel on the EDR, I would have to have the legal one first? Or could I do that after? I hope that makes sense.