'Doption Smoption

How do I explain the significance of an adoption day date to my 4 year old?  He's like "Yay!"  - picking up on my enthusiasm (which quite honesty comes from the additional news that this whole thing somehow turned out to be free!)  "What's 'doption'?"
   "Uh...m" I stumble.  "It means I'm definitely always gonna be your mom."
   I don't even know why I'm saying what I'm saying while I'm saying it.  He reacts as I should have expected: with a confused brow, a pause, a shrug and eventually a patronizing "Oh... Yay..."
   It's not his shirk.  It's just absurd.  It's amazing just how absurd it really is!  You can't fool a kid.  They haven't been corrupted yet.  He knows who his mom is.  He knows who his Ema is.  He knows his parents.  He knows he doesn't have a "father."  He does have a very nice uncle upstate who was kind and generous enough to help his lesbian niece and her wife have a baby biologically connected to both of them, but my son doesn't care nearly as much about exactly how that help occurred.  He doesn't ask questions or make strange assumptions.  He knows the truth.  His parents made him.  Where do babies come from?  Babies come from mommies.
   And I tell people and get these half/half kind of reactions.  My friends and fellow lesbian moms are all happy because they understand the length of time we have had to wait for this (4.3 years) and the amount of energy it took to get.  My straight "ostrich" family are flabbergasted that A - I haven't gotten it yet, or B - I even need it.  And some of those "B" people are actually angry.
   Our marriage wasn't legal when we started all this, and yet it's legal enough now to undo the necessity of this adoption - some places.  There are judges turning down these adoptions because the parents were married at the time of birth.  But there are 17 states where our marriage is legal, and 33 with specific laws meant to ban our specific marriages from being legal.  We have to file together now federally, but lose the tax break an adoption affords.
   I inseminated my wife, - I did.  Nobody else was in that room with us, yet I'm a part of a huge culture of "other" mothers - mothers who straddle both roles (mom aka "dad") but always do so deliberately, despite all obstacles both natural and human-made.
   There are no "accidents" here.
   These children were fought for, dreamed up; these children were researched, justified, expensive; these children were family goals lines before they were ever conceived.  These "moms" are amazing.  My son is right.  Shrug!  Shirk!!  Eye roll!!!   Give me my paperwork and my picture of my family "legitimized" and keep your scare quotes forever.  And know that I got it free despite all your efforts to break us!  Why?  It's so crazy it can only be 'cause of God.  You can't mess with God.  God is love not hate!  Love is family not legality.  Moms are moms!  Duh.  'Doption Smoption!  What eves.  Lol