Open Forum

Their current policy and guide is linked.

There is also a strong discussion of this in Europe, as so much of Africa's artifactual heritage is housed there, a legacy of colonial theft museums have been selectively looking to repair. 

If you look into the controversy surrounding the opening of the Humboldt Forum, you will find leads.

Another intersecting angle would be to talk with someone at the Museo Nacional de Anthropologia in Mexico City- they actively try and get indigenous artifacts returned to them. I once had a conversation with someone there on repatriation who mentioned that they are often told objects can not be moved because Mexico is not a stable-enough country (?), replicating the colonialist narratives even in the de-colonizating process of repatriation. The stage of policy whereby a claimant is verified as reasonable or legitimate seems key, as does the degree to which museums look outwards and actively seek to return items vs making an inventory available with a claims process.

Hope this helps- it's really important work and I hope your museum finds a way to address your collection.