That's the dilemma that player face if they choose to marry with any of the 1st generation or spotpass character. Most player have their avatar marry 1st generation characters like Chrom, Tharja, Cordelia, Lissa, etc. for the 2 kids, but then one of the 13 kids will be left out. That one kid would be forever alone...
What are your choices? Do you prefer marrying 2nd gen instead? Is A-rank support still adequate for that one unmarried kid?
I usually end up paring my avatar with 2nd gen character because of that dilemma.
What do you guys think?