Advice needed.stretch/waviness in my geese edges
 

I have unpicked the top floral arcs from these flying geese blocks and am replacing the arcs with a different fabric. Because my geese are constructed of triangles I have a lot of bias edges which have been stressed in the process even though I was really gentle with my unpicking. As a result I can see I have some stretch/waviness in my geese edges. Is there anything I can do before sewing the new arcs on to help with this? I think I am going to end up with puckering otherwise.
Any advice would be most gratefully accepted as I have invested a lot of time in these blocks and I am fast losing hope of a successful finish to this project.

Spray starch and press. When sewing the new piece in, put the bias on the bottom. The feed dogs will help work in the fullness. Hope this helps.

After starch and press, sew a line of staystitching along the edge of the geese within the 1/4 seam allowance. Say 1/8 inch from edge and that will help prevent further stretching. Be careful not to stretch the edges as you stitch, let your machine feed the fabric.
Really beautiful blocks by the way.

Thank you Eva and Murphy224, I appreciate your advice and will do as suggested.

I do one of two things before I cut bias edges. I put a strip of lightweight fusible stabilizer on the back of the fabric or I spray the fabric with Terial Magic Spray.

I would do all 3 of these things to insure that it maintains the shape after restitching. The stabilizer will prevent sagging or shifting since this piece has a lot of bias cuts. Re-stitching is only a part of the issue.

Can you sew a line of stitches 1/8" from the edge just to hold it? Then sew on with 1/4". No need to remove the 1/8th stay stitch line.

Thankyou everyone....all advice noted and appreciated.

I agree with the above advice, with one small difference. After unpicking, I would hold a steaming iron about an inch above the fabric for about 10-20 seconds, then wait for it to cool, then do it again. This will help the fabric relax back into it's natural, un-stretched state. Then spray starch and press, not iron. Meaning, do not swipe the iron across the fabric. Move the iron only by picking it directly straight up off the fabric, then move it to a different spot and set it back down.