Using multiple apple-developer-merchantid-domain-association files to support Apple Pay through different payment gateways

I'm in the process of supporting Apple Pay through a 2nd payment gateway for some users, so I need to support two separate Apple Pay relationships. Both require their own apple-developer-merchantid-domain-association. I don't see how I can have both files for the one domain. Is this possible? Is there a workaround other than just replacing the old file with the new one and hoping that doesn't disrupt anything. That seems to be the approach taken by others (https://developer.apple.com/forums/thread/695538) but it is too high risk for me without any confirmation from Apple that this is ok. I'd also like to avoid having to setup a 2nd domain for these customers, since the current domain is already quite embedded in their operations.