Okay here is my silly suggestion: A You-Just-Missed-Him sequence. A series of dialogues instead of another mashup.
Like... I dunno. PURELY AN EXAMPLE:
Tim n' Time tumble into Batman, but there's villainry to be thwarted so they spontaneously team-up. And then Tim n' Time go off to drop Lobsang back in Bludhaven or whatever.
Batman runs into Three, o hey Robin that was quick, but no time for explanations! We have to go beat up Two-Face and rescue prisoners! OFF THEY GO and split up when they get there. And here's Wingboy, oh hey Batman about time you got here, we'll take the front you take the back. And around back there's Nightman, geez Batman where have you been.
And then they look for Robin in the captives, and he's not there. DUN-DUN-DUN.
Don't necessarily have to be RP'd out nose-to-tail, but that's how they'd read.