Originally Posted by GrannieAnnie

Make a lining bag same size as outer, sew all seams including the bottom seams. Lay the out bag out with outside out--main fabric showin------pin the straps where you want them with raw ends up and strap laying on the outside of the bag. Pick up lining sewn with all seams but top. Slip outer shell into the lining bag. Pin & sew all the way around the top BUT leave an opening of maybe 5-6" The straps should not be seen yet. Pull one bag thru the hole and finish off the upper seam by hand or even on the machine.

Now, I have to say, this makes perfectly good sense to me, but I've been doing it for decades. So ask if it's as clear as mud.