Prevent a quote line to use discount after selecting surcharge modifier

Hello,

Currently, it is possible to lower a unit price on a quote line that uses a surcharge modifier.

Is there a way to disable this?

In my case :

I entered a line in my quote. Its list price is 614.

In the line details, I added an adjustment to use a surcharge modifier. A pricing formula is used to default the list price.

But if I want to lower this price, I can do this although the modifier is a surcharge type.

Is there a setup that could prevent this to happen?

Many thanks for your help.

Alex