Thanks for all your input girls.
My intention was to machine stitch with a decorative silver stitch. Hand stitching probably could be an option but I am running short of time.
I did Google metallic thread and read about the Metafil (Schmetz)needle but when I went to my LQS today they did not have it or any other brand. They also didn't have any metallic except a very bright multi-coloured one (which was a round thread) - but not quite wedding stuff! They did have a Sulky thread in a paler suitable colour so I bought it just in case I don't get anywhere with the metallics.
The bridesmaids fabric (which I am using in parts of the quilt) is a lavender/blue which you would think would be easy to match with fabrics and thread but it turned out to be very difficult to match. It's one of those shades that changes depending on whether you put blue or lavender next to it. I just needed to add a few touches of something and I thought the silver would be a way out but perhaps I am just complicating things for myself by trying something new when I'm under pressure to get this done with limited time. Between family commitments and work I don't have a great deal of time to get this finished if I want to give it to DIL for Christmas.
I will need to look up Yenmet metallic thread and Sewer's Aid as I am not familiar with either of these.
Thanks everyone for giving me some information and the opportunity to think out loud. I will see what I can find by this weekend and make a firm decision then so I can get cracking on it.