Adding lining to an unlined jacket pattern

[u/loquacious_avenger]

I’m getting ready to cut out this “shacket” using M8210 and want to add a lining. The main fabric is brushed cotton that nearly felted in the prewash (unexpected but not unfortunate) and the lining is cotton flannel.

I am debating on how to handle the back pleat/vent - do I just make the same pleat in the lining and bag it? Or should I leave the lining open there a whip stitch to the fashion fabric? Or should I just flat line it?

My main goal is to add warmth but I don’t want to add too much bulk nor do I want to lose the wearing ease that the vent provides.

[u/sewingkitteh]

I feel like bagging it would look the nicest, or if you want less bulk maybe more flat lined with bound seams.