I have family visiting me from UK at Christmas. Picking them up in Phoenix and driving to Kino Bay. I want to try avoid the backup at KM 21 for visas due to the huge numbers of paisanos going south f...
I believe what we call a Mexican 'visa', the FMM, is not a real visa. It is for the use of US and Canadian citizens only (and maybe central America). For a foreign national, I think they must get a real visa from the local Mexican Consulate. But not all Consulates handle visas, you might have to go to an Embassy instead. Call your local Consuate/Embassy to check.
Above all, I wouldn't drive all the way to KM 21 just to find out that your friends can't cross.