What proof of kinship i can give if we have kids but we're not yet married?

Candyce, as your case is not common, I think you need to take a paternity test for your children to get a blood relationship certificate for your children. Then take the kids’ birth certificates and blood relationship certificates to have them notarized. Then go to the embassy to authenticate those certificates, which can be used as kinship proof, just for your reference. You can consult the embassy for whether this method is feasible.