Shipping – I have 2 Drop shippers – Weight + Flat fee = Shipping COST

Is there a way to add Shipping WEIGHT + Shipping Flat fee = Total Shipping cost.

The reason for this is that I use 2 drop shippers.

DS1 – Is bases on Weights
DS2 – Is based on Flat Prices

IF I sell a women Tshirt from DS1 the price is $3.15 (based on weight)
IF I see a Kids Tshirt from DS2 the price is $5.00 (Based on flat-rate)

So the shipping will be in the cart $8.15 as I have to pay each DS shipping fee’s.

All of my Items from DS1 I have the weights set up
I just have 1 item right now from DS2 and I made up a Shipping CLASS called DS2

But now I’m stumped on how to get the WEIGHT and the Flat fee to Add them together for the shipping rules..

As now it shows all of them in the list.. for the customer to choose.

I’m trying to use Flexible Shipping FREE not sure if I go to the PRO that this can be done.. As I’m not the first one to have this issue. I have sent them an email as well – but just asking the community to see if it can be done.

Thanks