Well, thank you for your comment.
#1 It's a myth to think that polygamy automatically results in additional children. Brigham Young, for example, lived a long life -- had 27 wives & 57 children -- but had no children with 17 of those wives -- and only 2 or 3 of them because of age reasons. That means that 14 of those wives lost out on 3 or more kids -- and several wives didn't likewise reach the demographic average of the 19th century. Therefore, 50 less kids were probably born because of Brigham's hoarding of women.
#2 The "be fruitful and multiply" comes from Gen. 1:28 -- and we also need to look at Gen. 2:24 to review God's intention from the very beginning re: the institution of marriage: For this reason a man will leave his father and mother and be united to his wife, and they will become one flesh.
Now I didn't see plural people mentioned either in Gen. 2 (or Matthew 19 where Jesus talks about this same subject). Do you? And if marriage is becoming "one flesh" -- are you telling us that 2 wives and one man all become "one single flesh" in God's eyes? (Two "sister wives" become part of the same flesh?) Really?
If the rules were changed, I'd like to know chapter and verse - and not some convoluted reasoning that doesn't reference the Bible.
Good request. Even before Solomon took many wives, these verses existed:
He must not take many wives, or his heart will be led astray. (Deut 17:17)
Do not take your wife's sister as a rival wife and have sexual relations with her while your wife is living. (Lev. 18:18) [BTW, going against this injunction frequently happend with 19th century & early 20th century Mormons -- men often married the sisters of their wives]
So, despite the injunction of Dt. 17:17 & Lev. 18:18, we see what happened with Solomon:
He had seven hundred wives of royal birth and three hundred concubines, and his wives led him astray. (1 Kings 11:3)
We see EXACTLY what God warned about in Dt. 17:17 happened to Solomon!
Besides, if we're going to start using OT figures as "marriage models" I doubt you'd be OK with 700 wives & 300 concubines
And I think, you'd also NOT be OK with how Jacob came to pick up a second wife, right? Otherwise, when your daughter gets married, just slip in a substitute sister first -- so that the groom doesn't know it til he's into his honeymoon. Then if he stills want your other daughter, make him work for you for years on end if he wants the other one. IOW, deception was the basis for Jacob's polygamy -- and that's not grounds for a Christian marriage, is it?
As for Abram, it wasn't his idea and it wasn't God's idea to "encourage" Abram sleeping with a servant girl that everybody (except his wife) still referenced as nothing other than a servant girl after he slept with her -- including an angel. In fact, what became of this arrangement? (The person who became the clan leader of the entire people group which embraced Islam)
I still didn't see the reference where it says no more than one. As a matter of fact if you take your deceased brother's wife in accordance with the Scripture and are already married, you have been directed to have more than one wife.