User blog comment:PlantyThePottedPlant/Random Topic Blogging II: Electric Blogaloo/@comment-4643543-20120116063101/@comment-753210-20120116100518

Hmmm.. she's most likely Mexican. Here's the link to her in the canon wiki: http://phineasandferb.wikia.com/wiki/Mrs._Monogram

I think it's Vivian (Isabella's mom)'s sister or best friend or something.