If your BF earned more than $4050 in 2017 he cannot be claimed as anyone's dependent. Your grandma cannot put your BF's W-2's on her tax return. BF needs to file his own tax return and face the music with the child support he owes. His tax refund will likely be seized by the IRS to offset the back child support.
Remember that W-2's are reported to the IRS by the employer with the employee's Social Security number on them. No one else can put your boyfriend's W-2's on their tax return.
If your BF earned more than $4050 in 2017 he cannot be claimed as anyone's dependent. Your grandma cannot put your BF's W-2's on her tax return. BF needs to file his own tax return and face the music with the child support he owes. His tax refund will likely be seized by the IRS to offset the back child support.
Remember that W-2's are reported to the IRS by the employer with the employee's Social Security number on them. No one else can put your boyfriend's W-2's on their tax return.