You need to make a decision quickly as your insurance company expect you to adivise them of the incident within a certain timeframe, usually 24/48 hours.
If you claim after this time, some of them get "funny", refuse your claim, but log the accident - which will increase your premiums on next renewal.
If you claim after this time, some of them get "funny", refuse your claim, but log the accident - which will increase your premiums on next renewal.

but she isn't claiming from them - if she does then she'll have to pay her excess and then claim it back later. She's claiming from the OP's insurance and doing it via a 3rd party (her own insurance) just adds an extra layer of admin, meaning costs, delays, and chinese whispers
, my bad if I got it wrong, my point was simply both people regardless of fault have to tell their company somethign has happened, even if not claiming.