Suppliers Functionality Flat Fee Shipping Costs

I have a customer who uses the suppliers addon.
As per the documentation:- If a customer buys several products from different suppliers, several shipping methods (assigned to the suppliers) will be used in the order. The shipping cost will be summed.

However they would like to only charge the shipping costs once and if possible change the shipping location to their own address instead of the customers.

I have a bit of experience changing tpl files, but not very much.
Would this be a simple change or would this mean extensive changes to the code?

If it is difficult to make these changes, could somebody give me an idea what it would cost to have these modifications made for me (both options: flat shipping costs and both flat shipping costs and address change)?

Extra info:

Current CS-Cart version: 4.3.8 (still has to do last few updates)

Please check addon settings

http://prntscr.com/eyab4x

I think you misunderstood my question.

The mentioned setting only displays the shipping methods seperately or as one.

For example I have 2 different suppliers one that uses shipping method a, the other using method b. Both cost $5,-

With the option off it would show something along the lines of:
Shipping costs $10,-

With the option on it would show something along the lines of:
Shipping costs:
Method A $5,-
Method B $5,-
Total costs $10,-

But the total cost would be $10,- no matter which setting I choose.

That's not what I'm looking for, what I want is there to be fixed shipping costs, no matter how many suppliers there are in an order.
So in the above example it would be $5,- not $10,-

I think, you are not right. Please check

Setting enabled:

http://prntscr.com/eyl7r2

Setting disabled:

http://prntscr.com/eyl85s

The problem I'm seeing there is that you have 1 shipment method, my customer uses 2.

I think the costs only get added once if they are the same shipment method, not when theres 2, then both get added still.

If it works in this way, I am afraid there is no ability to set up shipping methods in the required way without additional code modifications.

Thank you eComLabs.

That is in fact why I asked for these modifications in the first place:

I have a bit of experience changing tpl files, but not very much.
Would this be a simple change or would this mean extensive changes to the code?

If it is difficult to make these changes, could somebody give me an idea what it would cost to have these modifications made for me (both options: flat shipping costs and both flat shipping costs and address change)?

We always try to find free solution. Please post your requirements here. Our manager will contact you with the free quote

Our team is also at your service. Please contact our CS-Cart developers to get a free quote.

Best regards, Alt-team.

Thank you both, I will contact you after the weekend when I'm back at work.