Hi Toohard
It's not a silly question if you don't know the only way to find out is ask. Now i'm still learning myself but as far as i understand age doesn't exclude them from pedigree matching but some people when trying to match stallions with mare's don't look back past 4-5 generations. Now i'm not sure what you mean by "xx" line mare but if you mean say 3x3 cross that would be say a filly by Art Major infoal to Rocknroll Heaven and that would give you a 3m, 3f to Artsplace. I hope this helps.