Looking up, in 2011, Alexandre Frota returned to "Malhação" as a guest in the "Ribeirão do Tempo" season. Marcia Impérator hosted a TV show but doesn't seem to have appeared in "Malhação" at that time. Maybe they were together in a different context, like a TV special, charity event, or a celebrity pairing in the media. There was a Brazilian reality show called "Dança dos Famosos" where they might have participated, but checking, they didn't pair up in 2011.
To sum up, the most plausible connection is Alexandre Frota's guest role in "Malhação: Ribeirão do Tempo" in 2011 and Marcia Impérator's hosting role in a TV show, possibly coinciding if they were both in a particular event or episode. However, a direct collaboration isn't confirmed. I should present the known facts and clarify that there might be a mix-up in names or events.
Wait, there was a 2011 episode of "Malhação" where Frota made a guest appearance, and maybe Marcia was involved in a separate part. Alternatively, could there be a dating rumor between them in 2011? Not sure. Need to confirm the exact 2011 context.
Alternatively, maybe a Brazilian movie or project they co-starred in. Not finding a direct co-project. Perhaps the user is referring to a story where they were both mentioned in the same context, maybe a charity event or public appearance in 2011. Another thought: "brasileirinhas" might also refer to a beauty pageant or something, but "2011 brasileirinhas" isn't a known event. Maybe the user is misremembering the term.