There is nothing for you to do structurally. What you're proposing is third person scenes with first person transitions. The technique if very popular in ghost stories because the first person cannot create confusion by appearing in a scene.
Technically the style is no different to first-person. Any scene in a first person story where the first person is not present is third person.
Here's an example where the first-person is "Granddad" (Coach Cole). Granddad is the narrator and narrates at the beginning of most chapters.
I really didn’t expect to set eyes on Errol again for the remainder of my years. Back in 1999, my eldest grandson had been sentenced to an undetermined length of imprisonment after he’d taken revenge and killed two of his father’s murderers. I didn’t write him. He never wrote me. His presence here, today, unsettled me. I needed to take some time alone to consider the implications of the return of the fallen one.
Half-time, and we were losing. The troops needed to be rallied. Plans and strategies needed to be actioned. In my absence, and as team captain, Wesley stepped up, made my excuses, and talked to the team. In the light of what had just taken place, he seemed extremely focused.
"We're still in this!" barked Wesley. "Apart from the one brief lapse in our concentration." His mind wandered to Stuart but he deliberately cast his eyes in the opposite direction. "We were more than holding our own out there. We don’t need to panic. We are only a goal down. We need to start smartly, and we need an early goal. And my granddad, Coach Cole, is right.In some respects many of us are still boys, but it ain’t like that’s a bad thing. It’s our strength, and their weakness. . . ."
- The first two paragraphs are known as a transition (narrative taking us from one scene to the next). The narrative in the second paragraph reiterates the narrator is not present during the scene. The following paragraph returns to the 'live' story.