Find Living Relatives

Can anyone help !
im trying to find this lady ,she is the mother of my step sister.My dad (not biological) married this lady in St Albans Hertfordshire.Together they had a daughter Caroline Sewell,things didnt work out between them & when Caroline was about 10 months old her & her mother disappeared,my dad never saw them again.He met another lady & they had 2 more daughters Joanne & Deanna,unfortunately this relationship also failed,eventually he met my mum & settled down with mum me & my sister,they went on to have another daughter & a son,all i can tell you is Carolines grand parentd lived in the st albans area,her nan's maiden name was Van Der Heyden her grandad's Shepherd,i think Caroline's mum had a brother Philip g Shepherd. if anyone can help find Caroline i would be truely grateful,unfortunately our dad died 5 yrs ago,but she has 3 sisters & a brother who would love to meet her,thanks for your time guys .xxxxx Caroline was born in St Albans around the end of 1965 to the begining of 1966,my dad always had pictures of her as a little baby.i found a record for a Jacqualine Shepherd who married a man called Roger Wheeler in St Albans in 1975.Any help would be great as the family would be overjoyed to finally meet the elusive Caroline,thanks guys,kind regards Lisa xxx nudge