It sounds like the OP and management is handling this. Several posters suggest focusing on what Flirty is doing (flirting, chatting, we don't like seeing her perched on single guys desk, we think she's looking for a baby daddy) instead of working. If I were Flirty's manager, I would not care what she is doing so long as her work is getting done, and it would make me raise an eyebrow to be told specifics of what Flirty is doing by other employees. To me, it comes across as borderling creepy and unproductive for coworkers to be tracking what Flirty is doing.
What I WOULD want to hear is that Flirty (or others) is not getting her work done. It doesn't matter why not - she could be appearing to be working sitting at her desk when really she is online chatting with someone (for that matter, any of the other coworkers could be doing that too). I think the OP should focus on what management will care about - Flirty is not doing her share of the work. Leave out all of the "we think she's flirting" junk. To me, that comes across as petty. Flirty not getting her work done is what I would care about.