Can a lawsuit be filed against several organizations at the same time?

My aunt lives in a HUD seniors’ building in FL; the on-site manager has been psychologically abusive to her: she has threatened to raise her rent & has intimidated her in other ways. HUD doesn’t have jurisdiction over such abuse because there is no federal law which covers elder abuse. There is, however, a state law which does: it requires the owners of the building to post the state statute on a common bulletin board notifying the residents of their rights on elder abuse. The owners of the building have not done this, &, it is my understanding that the owners don’t even know such a state law exists. Other than the owners & the on-site manager, there is a third party involved: the managing agent. This is a corporation that is supposed to oversee the on-site management, but they aren’t doing so. The managing agent does not take the complaints about the on-site management seriously. Is it possible to file a “combined lawsuit” against the owners, the managing agent, & the on-site manager?