1. I can see Eliza Ann's birth on FreeBMD but cannot find her baptism.
2. I have a Charles Frederick Newnham married to a Caroline STANLEY (NOT Seager - I cannot find any Newnham/Seager marriages) in 1855 in Gillingham, Kent but I only have three children for them - Frederick James, Henry and Albert - although there seem to be unusually large gaps between their births suggesting that there were other children.
3. I can also see an Eliz A Newnham with Jno. & Frances Seager in 1871 (no relationship shown to Head) & in 1881 described as his grand (?) child. But note the 21 year(!) difference between the ages of the Jno. and Frances.
4. Finally, I have Caroline's parents as James Stanley and Elizabeth Hoare.
I would be interested in exchanging information with you about your ancestors as it seems likely that we are related. Charles Frederick Newnham is my great great-uncle.