Inserting a panel fabric into backing
 

I want to use a fabric panel as part of my backing on a quilt. I realize that is not the problem. My question is as I stitch in ditch on front of quilt it will go through panel and mess it us (as looks). How would you accomplish the stitching through this area? Thank you in advance for your suggestions.

As Angela Walters says, you can only worry about one side of the quilt. Decide which one is most important to you and quilt for that side. That being said, if you use a fine thread in a closely matching color for the panel side it shouldn’t be too noticeable.

I agree with Angela (as usual)

Could I use let’s say lt. gray for stitch in ditch and when I come to panel area switch to invisible thread though area of panel then back to gray? Or does invisible thread show up? Thanks. Or is this impossible?

stitch the quilt before adding the backing (panel).

Angela Walters is correct--you can only worry about the quilting on one side! But you could select a bobbin thread color that blends in so it's not visible on back--or use an invisible thread like Superior MonoPoly (loosen top tension a tad) on the top thread and flip over the quilt so the invisible in on the actual back.

You are so smart!!

What about quilting the top with flannel as the batting. Then quilt the panel with flannel as the batting. Then I would stitch both sides today. The quilting would not need to be heavy. Just a thought.

On my two sided quilts, I chose to quilt for the side I considered to be the front. The echo quilted flowers from the front on one simply added a design element to the back. The second one had pictures on the back so I did try to not sew through any eyes. No reason, except it didn't feel right to sew on my granddaughter's faces.
I second the choose a side - maybe use a blending color like pale gray on the back.

you will still see the texture created by the invisible thread, but it will be better than a contrasting color. however, I was told once that you are not supposed to use invisible thread in the bobbin. not sure why, or even if that it true, but may want to look into it.