optns https://apibeta.familysearch.org/platform/tree/persons//merges/
The OPTIONS method supplies information about the viability of this merge, using the Allow HTTP header. If this merge is viable, the Allow will indicate that both GET, POST may be applied. If the merge is available when the roles of the survivor and non-survivor are switched, a Link header will be supplied linking to the "merge mirror." When the merge is NOT viable, the Allow header will NOT include a GET or POST. The Warning header will contain details as to the reason the merge is not viable.