Form 8615 and definition of "full-time student"

Please HELP!  Re Form 8615

My daughter who was 22 at the end of 2021, does not meet the "full-time" student definition regarding having attended a college within at least 5 months during 2021 (she was only attending college Sept-Dec).  So we can't claim her as a dependent on our joint return.  However, during the Fall semester 2021, the total credits of classes she took considered her full-time (although she didn't earn all the credits).  Her 1098-T is marked for "Checked if at least half-time student".  

 

Under the Who Must File, it states Form 8615 must be filed for any child who meets ALL the following:

1.  Child has more than $2,200 unearned income (YES)

2. Child is required to file tax return (SINCE I CAN'T CLAIM HER HAS A DEPENDENT, AND SHE HAS EARNED INCOME, SHE NEEDS TO FILE A RETURN-YES)

3.  Child is either:

           -Under 18 (NO)

           -Was 18 on 12/31/21 & didn't have earned income more than half of child's support (NO), or

           -Was a full-time student 19-under 24 yrs old @ end of 2021 (MAYBE?  WHAT IS DEFINITION FOR FULL-TIME STUDENT FOR THIS PURPOSE?)

4.  At least 1 parents was alive at end of 2021 (YES)

5.  Child doesn't file joint return for 2021 (YES, SHE IS NOT FILING JOINT)

 

Then, if she is considered a full-time student regarding the 8615 and this form needs to be completed, is it completed w/her tax return OR my return as the parent? 

 

Then, to make it more complicated, I have a second daughter who can say YES to all 8615 questions (she's a full-time student based on the 5-month definition and # of credits in Spring and Fall 2021) so she qualifies as a dependent on my return and she is filing her own individual tax return.  Again, is the 8615 filed w/her return or mine as the parent claiming her as a dependent?  AND, if you confirm they both are required to file Form 8615, even though only one of them is on my return as a dependent, do they both have to put each other's info on their respective 8615's along w/our parent taxable income?

Sorry for length but head is spinning!