Conditions + Specialisms

I need help with a patient. A 3 y/o with arthrogryposis. He is above average with cognitive skills. His 4 limbs are flaccid, with slight flexion contractors in B elbows and B knees. His abdominals are very strong with movement in all planes. How do I help him don/doff a over head shirt and don/doff pants. I have searched youtube and brain stormed to my fullest capacity. Has anyone had success with adaptive tools or environments? Any help would be excellent. I am in an outpatient setting at a Children's hospital. Thanks in advance!