That would be a desecration of a chapel, and desecration is forbidden. Satanists, for example, are not permitted to desecrate cross, communion, or bibles in military chapels.
Catholics, orthodox, and other Christian chaplain in the lineage of historic Christianity should request separate chapels, and should request of their denominations statements affirming that homosexual marriage inside their buildings would be a desecration.
Christianity should request separate chapels,
Oh and who is going to pay for this huge expense. We only have 15 trillion in debt and now you want to add another trillion. Nice. There must be other options than this.