elfquestfanAZ said: So there is about 10-12 years of age gap between Windkin and the twins.
You are right about their age gap at birth
Do the "early issues" include the Kings of the broken Wheel
story arc? If not the following will contain SPOILERS ...
Rayek has kidnapped the Palace, with Suntop and Ember in it, to the far future. When the Elves were reunited only one or two dasy had passed for those who were in the Palace. Suntop and Ember were still preteens.
For the other Elves it was wait of 10,000 years. The mortal Wolfriders went in wrapstuff to survive the time. The immortals - including Windkin - were alive and active all the time.
Windkin is thousands of years older now than the twins. Old enough to have sired a whole dynasty of descendents - one son was an easy task.
EDIT: jorenm93 pinned the point while I was still writing! Must learn to keep my comments short. ;)