It's possible to set a new flag on a treatment which will ensure that every time the treatment is taxated a pop-up will ask for the correct amount of the treatment.

Go to Frontpage - Treatments - Diagnosis and Treatments and search for the wanted treatment

Find the correct treatment, add the flag called Require count on taxate and press Update.

Taxate the treatment and a pop-up will occur asking for how many treatments should be invoiced.

Choose the correct amount and press Ok in the pop-up( in the example below 3 treatments are invoiced).