Thank you for your question
My name is Clare
I shall do my best to help you but I need some further information first.
is it a condition of your mortgage that you do not let to family members?
Do you do your Buildings Insurance via the mortgage company?
Do your parents actually pay rent?
In that case you have no need for concern.
Yes you are technically in breach of the Mortgage Conditions but this would not justify the calling in of the mortgage - and does not invalidate the Insurance you have with the Insurance Company.
Please ask if you need further details
I am a solicitor in the East Midlands!
I would expect the Mortgage company to agree given the fact that you have a proper contract and payments have been made - but it is not the end of the world if you leave it for now.