You have a chance to have their offspring return to you when they grow up.

assuming of course they survive as a couple and don't get killed off... i sometimes dont bother any more they die so much in my games 

edit - the married couple not the grandkids - haven't seen em survive yet lol

Delmoroth:  I think your best bet is to make your sov female, then marry off your males.  That way you have control of the married couples (and can keep them safe), you still get half the children, and your females can lead your armies.

hey I always play a female SOV (thats me.. LOL)  My experience has been marrying a son off usually brings the other Sovs daughter into my court.  marrying a daughert off means they leave for the other sovs court.  So i keep daughters close, for service to mama me.  Sons I marry off and get daughter in laws who join my court.

There is a diplo advantage to another faction sharing 'children,  and grandchildren with your sov.  However, in one game, a sov who had my daughter in his court did declare war on me (forced, I think, my another powereful faction?)  Anyway, I ended up having to kill my daughter, who was with the army of that atttacking Sov.  Was a shocker when I first saw it.

Realistically, however, royals get mixed up in all sorts of politics, switch alliances, and wage wars of succession, or what ever with kin.  Check out how many wars have been faught over 'succession' . War of the roses comes to mind. Wish SD would figure out a way to put this in.

The primary benefits, as listed above, are a diplomatic boost with the faction and the potential for grandchildren down the line.

When married your male children will always stay with you and have the other faction's daughter join you, while your female children will always go to the other faction. Horribly sexist, I know.

When grandchildren grow up they have a chance to join either of their parent's starting faction. It seems weighted towards their joining their mother's faction, that is, your son's kids will probably defect away from you while your daughter's kids will probably defect back to you. It isn't set in stone, just seems like it happens that way most often.

Because children inherit the abilities of their same-sex parent you can end up getting the abilities of other Sovereign's this way. So for example I marry my daughter to Kul-Kulan's (or whatever his name is) son, they have a boy, that boy grows up and joins me, now I have a grandchild with the Organized trait.

The formulas that determine children starting stats are still a little screwy, for example even if both parent's have 2 base move I frequently get kids with 1 base move, which sucks. Also no matter how pumped my two parents stats are (STR, DEX, etc.) the children and especially grandchildren tend to "even out" to 10 (because the AI tends to not level their kids much so all their stats stay at 10). The only exception is Essence which has been stated to always be "50-100% of the higher parent's essence."

One thing I do before sending my daughter's off to marriage is level them up a bit and equip them with a basic set of armor. It only take 3-4 easy battles to get them to level 3, put the level ups in hit points or dexterity, and buy them whatever armor you can afford. This increases their survivability considerably even when controlled by the AI.

That's how I feel, the short term military gains are huge in this game. You can conquer half the AIs in this game on a large map in the time it takes for a heir to be born & grow up.

Thanks for the replies.

I have sent daughters and the faction still declares war on me.  Also, I usually conquer before any grandchildren could be useful.  I guess depends on how you play.  Still, for me I do not see the benefit (unless you want to be friends, but I always conquer hehehehe) of losing a champion with mana for the chance of having one, two or three more later on.  I first played by marrying them off, but it seems to me like a waste. I like the idea, but not having any other channeler unless you sacrifice essence, to me those champions are priceless and time wasted can hurt you waiting for grandchildren. IDK, maybe marry off the males and keep the females I guess, although I'm not sure if I had grandchildren come back to me through a son, but I know I did through daughters. I remember thinking when the daughter was really gone that that really sucked. lol

I'd rather have 3 or 4 more armies led by channelers, but again, I conquer, never make friends, and games don't last long enough for grandchildren to be useful. I do think the children now not having tons more than the parent in terms of mana makes it much better and makes more sense.