Glad you've got that sorted out, even if you don't know why Alice P changed her name to Olive S and then changed it back again.
And why choose Swinstead? Not very common.
Looking at Swinsteads with an Oxford connection. There's a Louisa Swinstead who married there in 1870, she was born in London, mother was Mary. I think it is the same Mary who died in Oxford in 1890. Possibly came to live with or near her daughter when she was widowed. But thet would have been too early.
If Alice did get to know a Swinstead family in Oxford, it would be more likely to be Rev John Howard Swinstead. In 1901 he was a minor canon and schoolmaster (of choir school) in Oxford. His first wife had drowned (believed suicide) in 1899 after a year of marriage. He remarried in 1901 Sep quarter to the woman who was matron of the school (same household on 1901 census) in Melton Mowbray. He was made vicar of Chalgrove and they had a daughter Muriel Mary there in 1902 and another daughter Joan in 1903.
Muriel became an actress under the name Oriel Ross. Wikipedia haas her age wrong by 5 years
https://en.wikipedia.org/wiki/Oriel_Rosshttps://chalgrovelocalhistorygroup.org.uk/murial-mary-swinsteadIn 1901 Alice Prior was in Cowley age 14, a visitor with the Fitchett family. Susan Fitchett (William's 2nd wife) was born in Woodstock, but I haven't found that she is related to the Priors
Perhaps she worked for the Swinsteads at some point and decided she liked the name