Combine Flat Rate with regular UPS

I have some products which are now going flat rate overnight (UPS Blue). I need to add other products which will be sent via UPS via either overnight, 2nd day, or ground. Is there a way to select shipping modules by category of product? How can I make these two different modes compatible? I need to get ZenCart to grok that one (or several) item(s) is overnight at one price (per shipment) while other items in the same order may be dropshipped via some other UPS rate and charged by their weight.

Has this been done? If not, which files should I attack? This is my first ZenCart development so I'm not up on its 1,000+ files yet. TIA

P.S: I checked 450 (of 3500+, I'm crosseyed) different threads before starting this one. It wasn't quite the same as other shipping problems.

You might have a look this module as a place to start but will need adjustment
See it Here

kobra:

You might have a look this module as a place to start but will need adjustment
See it Here

Excellent. I've downloaded it and will take a look. Thanks.