Bambu Studio requests

1st. I have a model I’m trying to print that has a separate model available that is a premade support. In PS I can right click on the main part, select add modifier and select the file that is the support. PS automatically aligns the two parts and then all I have to do is select supports:”modifiers only” and it prints that premade support. I cannot figure this out in BS for the life of me.
2nd. I have a different model that I am printing in a generic PLA pro(plus/tough) and it has two thin towers on each side, at about the same place the printer ends up snapping off the tower and I have a failed print. I’ve tried it twice and it’s broken it off in two different places. I would like to add a brim to just these towers as the rest of the model doesn’t require them but there is no way to, once I add a modifier, add a brim for only the towers, or remove it for the main part.
There is also not an option to add a tab to the corners of square models to prevent warping without doing a whole brim.