My parents are planning to visit the UK and Europe, and have engaged a tourism company for this. While reviewing the documents they sent us, I noticed that the field asking about friends or relatives in the UK was filled "no". As it happens my parents do have relatives there - an estranged sister and her family. But we haven't managed to contact them and get their details (messages have been ignored).
What information should we submit in this case? The travel agent is recommending that we lie and say we don't have relatives. I feel it would be best to say we do, and fill in the details as best we could (we know the city they live in, but no more), and mark the rest as unknown.
My parents have no intention of going anywhere near them.