Rational
Some businesses generate a lot of lines in the same move and account. For example there is the case of statement line being split a lot of time to pay many small invoices.
In such case it may be difficult for a user to understand the list of receivable/payable lines as the amounts do not match the actual payment amounts. But also consulting the list of lines of such move can be difficult.
Proposal
On a new module account_move_line_grouping we define a new model based on a query which group account.move.line by move, account, party, second_currency; sum debit, credit and amount_second_currency; compute a maturity range (min and max), amount reconciled. A Function field compute the list of lines grouped.
It adds the “receivable/payable grouped lines” relate on the party.
It adds on move form on the first tab the grouped lines.