From mechanical to aerospace engineering Hi guys

I'm currently enrolled in the selection program for AE. I'm pretty sure I messed up the tests and won't be accepted. I am really sad but i will be fine. So next year i will start my first year in mechanical engineering at TUD, which is my second choice. I really want to end up on AE. So my question here is, how do i get there as soon as possible. I read that i can finish the bachelor mechanical and do a masters in AE. (after taking a schakeljaar)

If i start mechanical in september and try to get in AE i could start AE in 2022, if i'll get in. But i was wondering, since AE and mechanical are really similar, if i could maybe skip some classes because i have already taken them or follow some classes from the second year or do i have to do everything again? I hope some of u have experience with this!!