In the 1841 census, which gives Mildred as the head of family, there are 5 children named. The elder children were all born before it was made a legal requirement to register births in 1837. Charlotte, the youngest, was born in South Killinghome in 1841. I found a birth certificate for the only Fulstow girl born in Killinghome in 1841. She was born 18 Jan 1841 @ 1am. The mother's name on the birth certifcate is Amelia Fulstow nee Cooling who was born in S Killinghome. There was no father's name. She had made her mark on the certificate, so clearly couldn't write. It could be a coincidence but I think statistically the chances of it being someone else are a bit slim.