I know Maddie can answer these questions herself, but she's not online right now and I know she wants to get this sorted ASAP.
Her second son was born in the US, of a marriage to a British spouse. She already had FLR when the child was born and was only temporarily out of the UK. Before coming back to the UK, some bright spark in one of the UK Embassies told her that this child needed a visa to enter the UK. Consequently, the child, who has the right to British citizenship, is currently in this country on FLR. I think she needs to know how to go about getting him off FLR and registered as a British citizen, which is what the embassy should have told her to do in the first place.