Become a necromancer + werebeast
Becoming a werebeast necromancer adventurer is something I did before back in the 0.34 versions when night creatures first became a thing, the trick is to become a necromancer before you become a werebeast, since werebeasts are immortal and immortals can't become necromancers, hence you can't become a necromancer ever if you're an elf or goblin. This is definitely still possible in vanilla, sine I just recently encountered one in fortress mode. Keep in mind that when you transform your zombies turn hostile since werebeasts lack the [NOT_LIVING] tag that means necromancers leave them alone.
- Marry, get a wife or husband, get children
All adventurers start out asexual - so, in vanilla, these are impossible. You can change this with DFHack's "fix-ster" script, though, which should theoretically allow adventurers to get married and procreate. I don't know a way to "choose" your lover/spouse, though; but if you retire a fix-ster'd adventurer and let them operate on their own for a while there's a chance they'll hook up with someone
As far as picking spouses for an adventurer goes, you can do that in fortress mode via dfhack with gui/family-affairs to force marriages. I'm not sure if this results in children working properly. This only works in fortress mode mind you. You can even force interspecies marriages with this command, though you need to use an argument that disables checks. Surprisingly if you use a script to force pregnancies between members of two different sentient races, it doesn't crash, and simply results in a child that's the race of the mother, ie Elder Scrolls rules, which honestly might be a nice and easy solution for Toady once that comes on the agenda if half-breeds are too annoying.