Church handbook policy disallows polygamous marriages in meetinghouses.
"38.3.4 Civil Marriages Held in Church Buildings," General Handbook: Serving in The Church of Jesus Christ of Latter-day Saints, accessed May 17, 2023
Civil Marriages Held in Church Buildings
A wedding ceremony may be held in a Church building if it does not disrupt the schedule of regular Church functions. Weddings should not be held on the Sabbath or on Monday evenings. Weddings performed in Church buildings should be simple and dignified. Music should be sacred, reverent, and joyful.
Marriages may be performed in the chapel, the cultural hall, or another suitable room. Marriages should follow the guidelines for proper use of the meetinghouse (see 35.5.8 and 35.5.15).
The Church does not allow its meetinghouses or properties to be used for any purpose related to same-sex, polygamous, unlawful, or other marriages not in alignment with Church doctrine or policy.
In rare circumstances, the bishop may allow the use of a Church building for marriages that are performed by someone who is not a Church officer or for those who are not Church members. He first counsels with the stake president. He counsels with the person who will be officiating to ensure that he or she understands the guidelines in this section. A member of the stake or ward council attends to ensure proper use and care of the building.
The bishop may authorize a livestream of a wedding performed in a Church building (see 29.7).