If you running shine, you can usually connect with another shine if you do a slight walk first. Otherwise you have to waveshine > dash > jc shine, which is possible (see kjh and druggedfox waveshine infinite peach on fd), but very difficult.
Usually if you get the running shine it's better to go after a lage Nair > shine, drill shine ,drill grab or just grab seeing as Marth goes really far and when you shine him from center stage on fd most of the time you when you shine him again he'll just snap to ledge. I think it's usually better to go for a jc grab up throw up air at low%s, up throw Bair off stage at mid%s, and jc up smash at high%. You can go for a jc upsmash at lower % if you think you can get an upair or bair, but I haven't tested that yet.
I've seen some go for running shine > upair to start combos, that's definitely worth exploring, but usually I see mango go for a Nair after the waveshine so he can get another shine