Great question Todd! “What to do when you’re not playing a solo?”
When I’m in a playing situation, I’m continuously asking myself, “what does this need?” Depending on the makeup of the group and the style of song, and many other factors, the answer to that question will be different. For example, if there’s no mandolin in the band, I might do more “chopping” rhythm. If there is a mandolin, but no banjo, I might play more rolls and kind of take over the “banjo” role in the band. If it’s a slow ballad, it may not need either of those things, but more of a simple, sustained note approach. So listen to what’s happening in your playing situation, see what it needs, and respond accordingly.
Another recommendation would be to study great records that feature great Dobro players. I spent a lot of time with the early Seldom Scene records, the Bluegrass Album Band records, and all the Tony Rice records. Those records meant a lot to me and I listened to them so many times that I learned every note that was played on them (even on the other instruments!). Each sound is etched into my memory…So dig into the records that you really enjoy and listen for what the dobro player is doing during the entire song, and not just the solos. This will give you a lot of ideas for what to do when not soloing.
And check out what the other instruments are doing also, this will give you even more ideas, options. I’ve stolen a lot of musical ideas from Tony Rice’s rhythm playing, Sam Bush’s mandolin chop, and Stuart Duncan’s fiddle playing. Hope this helps, really great question!