I currently train these on separate days. Was thinking of changing that to one day:

Flat bench x 3
Incline DB x 3
Incline Flyes x 3

DB Press x 3
Lateral raises x 3

Anyone train these two together? Thoughts please.

if you're trying to add mass, train them together ime. If you really want to train them separately, when doing chest, focus on 'isolation' type exercises (which excludes pretty much all pressing movements, which imo are crucial for chest development). The problem is overlap - the shoulders (front delt specifically) are heavily involved in a bench/db pressing movement, so doing a separate shoulder day is a little bit of overkill if you're doing any heavy pressing.

You may also consider doing front / middle delt on chest day, with rear delts on back day (that's what I do)

have doen in past , no reason not to

db press probs wont be as heavy as normal , so if your training for power that may be a problem