TRiver, you're my age! I was 19 in 1974 as well. You and I are no spring chickens. We are 56 years old.
"I am broody: I want to have children, I want to be part of my children's upbringing, and it is irrationally important to me to know that some/all of the children I am bringing up are related to me genetically."
You want to find a young fertile woman who will live with you and this hypothetical infant you want to raise, to nurture, to cuddle and diaper and bathe and play with. To spend sleepless nights walking the floors with it, to clean up its considerable messes, to deal with its tantrums and various psychological quirks and issues as it grows from a newborn to adulthood.
You are also polyamorous and expect a young mother (somewhere in her 20s or 30s, and therefore much less mature psychologically than you) of your imagined child will also be poly, and have a chance of being impregnated by another man.
May I just say, I am in awe of your energy, hopes and desires in late middle age.
Love withers under constraint; its very essence is liberty. It is compatible neither with envy, jealousy or fear. It is there most pure, perfect and unlimited when its votaries live in confidence, equality and unreserve. -- Shelley
Mags (poly, F, 60) loving miss pixi (poly, F, 38) since January 2009, living together since 2013
also loving Punk (monogamish, 42, M) since Oct 2015
"Master," (mono, 34), miss pixi's Dom for 2 years