We typically lived between 3000 & 5000 miles away from family growing up. My grandmother on one side would send a check every year (we didn't know till nearly grown) sometime between Halloween and Valentines (when she could afford it). It's what "bought/paid back" out xmas PJ's that we opened up every xmas eve. We ALL got new PJs on xmas eve. Parents and kids.
Talking with my mum about it later my grandmother was only able able to afford to send $10-$20. But we needed new PJs anyway... so that's the tradition that my mum started. She paid for them and Gma got the credit, a little like santa. Gma H sent us our new PJs. (They weren't "holiday" themed, just normal pj's... so we wore them to bed that night feeling special... and then wore them all year until we grew out). She considered it a "double" gift. A gift to us from gma, and a gift from my dad to his mother.
So that's 1 option. A unilateral "double" gift.
Option 2 is to not open presents from your mom on xmas, but save it for some other time.