Not really an AIBU but posting here so that people can vote.
Imagine you have two children. DC1 is very academically able, very confident. Autumn born, one of the tallest in their class. DC2 is not as academic, very quiet and shy. August born and very small for their age anyway, so by far the smallest in their class.
You live in an area where there is a super-selective school nearby. You are very confident that DC1 will secure a place there, but think it very unlikely that DC2 will do so. The alternative catchment school isn't great and you think DC2 will really struggle/get lost in the crowd. You decide that you need to find an alternative school for DC2.
DC1 secures a place at the super selective but you also put them in for an exam at a private school an hour's commute away, which is less selective than the grammar and where you think DC2 will also secure a place, especially with a sibling already there. DC1 sits the exam and scores so highly that they are offered an academic scholarship comprising 50% off the fees.
You aren't that well off so the 50% fee reduction will really help. However, the super selective grammar is, of course, free.
Would you
A/ send DC1 to the grammar and pay for DC2 to go to the private school (AIBU)
B/ send DC1 to the private school as it might increase DC2's chance of getting a place there (YANBU)?