discount price plus delivery expenses calculated in percent

[felixthenet]

Hello everybody... Joomla 3.6.2 and VM 3.0.18
I need to manage a discount user group in an unusual condition (at least imho).
I created a rule to subtract a good 25% from the final price, and this works applied to the GOLD group I created.
The problem is that to this discounted price i also need to add delivery expenses, calculated as a 4.9% of the initial COST price.
I cannot find a way to create a working rule. Any suggestion would be appreciated.
Thanks for your time... happy life to everyone...
Roberto

[GJC Web Design]

I would build a ship plugin that used the brutto price and calc'd the % and enabled for this shopper group