Su - user & bash scripting?

I'm compiling the LFS Book into one giant script for personal purposes and yes I know Linux From Script exists although pretty poorly imo, but my question is this: Is it possible to continue a script after the use of the command " su - user "? The  command acts as if another user was logged into that prompt and therefore it cancels the script. Would making two scripts and giving the new user access to the script "su -c 'exec /path/to/second/script' - user" be a viable option or would that mess up file permissions on the LFS system?

nope, won't mess up anything, su -c is the correct solution lol.

Tried it and got this error

bash: cannot set terminal process group (-1): Inappropriate ioctl for device
bash: no job control in this shell

last line run -

su -c "exec ./" - lfs

yes, you can't run an interactive process without job control lol.

either avoid starting an interactive process, or add job control.

I tried using set -m on both scripts and it never worked. Any tips/advice on how to add job control as it isn't something i've had to do before.