Mary,
so far i have found,
B.M.D.
Martha A. Chapman=Sidney Young,Salford,8d,578,march QTR 1934
Sidney Young,Birth,Bath,5c,479.SepQTR,1909
Dorothy Young,Birth,Bath,5c,480,SepQTR,1909
1901 Census;
Charles Young,29,Somerset,wrington,somerset,clevedon,porter
this suggests he married between march1901 and 1909,however if there really were another 6 children(average 1 per year) this should mean they married between 1901-1903/4.
This is where i will search st catherines index
Paul