Can reproduce the photo again onto a different fabric ... muslin perhaps. That would be more stable than the jersey knit.
Agree with the others to keep the focus on Mom and Dad with simple borders. Blacks, whites, and greys - and if you use the T-shirt ... use the mint green as a binding.
You CAN use some fairly intricate pieced borders to really frame Mom & Dad but use borders that will point toward the center drawing the eye inward.