D.R.
Hi B.,
I don't have any first hand experience with this issue, but can defiantly see why it would be important to you. I took a moment to try googling your request, and had some lawyers websites pop up. You might try going that route to get a list, and then calling them to discuss your particular situation. I do know firsthand about how important it is to pick the right lawyer, so I wish you luck.
My google search was "kansas city and lawyer and gay and custody" and you could try variations of that nature to expand your search. Or, perhaps you could try researching on a site that caters specifically to the gay/lesbian community - as I am sure this is a common issue.
Good luck to you in your search and all of the pending work it will entail. Working with lawyers is a long, expensive process but absolutely vital to protecting yourself and your partner and son's wishes.
I hope for the best for you and your family, and I wish you a wonderful New Year!
D.