I’m assuming that you have a workflow that calls for multiparty FHE and I think that this thread will give you the answers you’re looking for, albeit indirectly; it should give you an idea of how to use multiparty FHE: t-out-of-N Threshold FHE in OpenFHE
From what I can see, you might be able to generalize the ideas presented in this function: UnitTestMultiparty but bear Yuriy’s most recent comment in mind:
For more general information on multiparty FHE see PALISADE Webinar #4 - HE Tutorial Series Part 5: Introduction to Multiparty Homomorphic Encryption. The video itself targets PALISADE, the precursor to OpenFHE, but the concepts are the same.