Can you reopen or open a new child support case

(Minnesota)

My husband was paying child support to his ex, but the child had dropped out of school, she is 18 now - so we got the case closed.

Now the child has moved in with us & we put her back in high school to get her high school diploma.

My question is... can we reopen the existing case, but have the ex pay us child support now??? Or if we can't reopen the case & have it switched because she's over 18 we can not open a new case???

Thanks!