I sing with both a group of musicians in a session and in song circles. I agree that one of the main problems with singing is sessions is that it is difficult to just jump in and hit the right note and mood for a song. I also find it difficult to interupt musicians who have played together for such a long time.   sometimes I am enjoying the playing so much that I don't want to interupt.   However, it did not take them long to treat my voice as one of the instruments, listening when I sing solo ( as they would listen to each other doing solos) and joining in both instrumentally when they could or in choruses. They now tend to push me into the first song as I am still a little reluctant.

In some ways I find it more flattering that they enjoy my songs than when I sing at song circles but I rather think that it is the novelty value.
J