Tip: When you are submitting a manuscript to a publisher, do just that–submit A (as in, one) manuscript.
Just this week I’ve received 4 submissions of multiple manuscripts in multiple genres all at once. When I get an e-mail that has 18 attachments–that’s 9 query letters and 9 FULL manuscripts, ranging from picture books to historical fiction to romance to gritty realistic drama–it makes my head spin. And I don’t mean that in a good way.
There are just so many reasons why I don’t like that.
Don’t do this. Pick your best one and send it. If you get a positive response, but it’s rejected because it’s not a genre the publisher does, or they’ve already got one like it, or they ask what else you have, then query another manuscript.