Remove Christmas Decor Background

I have a single high-resolution family photo where a fully decorated Christmas tree and related ornaments fill the background. I only need that festive backdrop gone and replaced with a simple, neutral plain wall that matches the existing lighting and depth of field. Please leave all other elements untouched—no color grading, tone shifts, or retouching on any family member.

Deliverable: a layered PSD (or TIFF) plus a flattened JPEG in the original resolution with the new, seamless wall in place. A same-day turnaround would be ideal.