Hi there Carly, I've been waiting for other quilters to reply to your question, as I've never actually hand quilted a Grandmothers Flower Garden Quilt. But my gut feeling, would be simply to continue doing what you're doing - quilting inside the border of each "petal". I think this genre of quilt generally speaking, lends itself to simple quilting, to allow the patternation and variety of fabrics to be admired in their full beauty. A busy quilting pattern might detract from the lovely work. How lucky you are to be given the opportunity to complete a quilt that was started with great intentions so long ago. Thank goodness the quilt was kept. We'd love to see a photo when you're finished. Happy quilting
Cheerio for now