Marriage service in non-WELS church?

I understand your question to be one that rules out any participation in the wedding service by clergy, musicians or other worship leaders outside our fellowship and addresses only the venue of the marriage service.

With that in mind, a prospective bride and groom could secure another church building for their wedding to be officiated by a WELS pastor. The situation would not be that different from a mission congregation that rents worship facilities from another church.

With this situation, the bride and groom would do others a service by explaining the re-location of the wedding—perhaps occasioned by the guest list and the size of the church sanctuary.