Like many people, it saddens me that Martin the Warrior never had a son or daughter, nor did her even fall in love again after Laterose died. I know Mr. Jacques has his reasons for what he writes, but here's what I feel should have happened.
In mossflower, Gonff has a sister named Lucy. Only she isn't present in the story because a 2 years before Martin and Gonff meet, she leaves on an adventure and hasn't returned, Therefore Gonff is now certain she is dead. Years later in "legend of luke". Lucy comes to Redwall hearing that her brother is there. Reuniting with tears and hugs, Gonff introduces her to his wife, his son, and martin. She goes with Martin and Gonff on their journey to find out about if Martin's father is Alive. As the story progresses, Martin gets to know Lucy, and starts to tell her how sad he feels, but cannot tell her why (remember how he promised never to tell anyone about rose), but at one point he does. In the end, Martin and Lucy get married and have a daughter named (don't know yet, you guys decide) being the cousin of Gonflett. And that's how I think it should have ended.