I will be visiting my friend in Glasgow come August. I will be staying with her in residence in Glasgow until the 28th after which we will move out and spend a couple of days in Brighton and some other places until the 2nd of September. Obviously we'll be looking to book Air BnBs for our trip and I plan to show the full itinerary during my visa interview. After the 2nd, I plan to stay with my mother's relatives in London for 3 days and fly out of the city. Question is, will I require an invitation letter, plus documents showing my mother's uncle is a national? I already have an invitation letter from my friend showing I'll be staying with her. Will I need to ask them to provide the same for the 2 days I'll be staying? My issue here is that they're old, and I don't want to bother them asking for their formal documents showing they own a place in London. Or is it better to modify my itinerary to show that I won't be staying with them, and instead show a dummy booking for a hotel.
Will it not look dubious though if I hand in an invitation letter from my friend, showing that I have accommodation for the first few days and then there's no proof for the rest of my trip? I'm assuming a detailed itinerary will be sufficient?