What if you only want part of your top lined? Can you do that? I don't see why not. This top had a nice lacey look that I chose not to cover with a fabric liner. It made for some interesting tan lines. So, I simply cut the fabric smaller than the actual bra cup and sewed it in the area I wanted to line. I tucked in the edges of the fabric the usual 1/2 inch and had no problems with it.
I still used safety pins to hold the fabric in place while I hand stitched the liner in.
Once I succeeded in getting a liner in, I relaxed and started having fun with making crocheted bikinis. You can, too!