I objected to a neighbour's carbuncle planning proposal recently. I've never objected before but I've learnt some interesting and surprising things. I'd always assumed that if you had a financial interest or any other interest where the applicant would benefit, then you needed to declare it. Another neighbour is a close family relative of the applicant and has fulsomely submitted a supportive endorsement of the application. They've also persuaded other people (some not even resident where we live) to support the application. Nowhere in their submissions have they declared their family interest. Therefore, in the list of comments, our objections are completely subsumed by these votes of support from people who were not going to get involved either way before or would not even have known about it.
I checked. Apparently, you don't have to declare a family relationship when you support a planning application. That really surprised me.