Grouping purchasing rules

The desire is to have an option on purchase invoices that all lines are grouped together.

The operation is as follows:
Click on button 'Group lines' then a popup follows where you can select the number of grouped lines. Here you can enter any number.

After entering the number there is the possibility to enter a description/amount per line, whereby the total amount on the purchase invoice during the creation of the purchase invoice is kept as the leading amount. If this amount is exceeded, a message is displayed and the user can choose whether or not to take this into account.