List function with Sum?

I have a subquery that retunrns multiple lines. To solve it, I have used the List function. The separation of List function is comma.

TblBill is in the main query with many other tables.
(Select List(tblBatch.batchnr) From tblBatch where tblBatch.tr_id = tblBill.kfr_trans_id ) As Batchnr

This subquery returns: B12, B13, B14, B43 and so on...

Now I want to use SUM from another field (quant) from table tblBatch in the subquery and then separate those with a line break instead of comma.
Batch number may occur several times and I want to summarize these

I want the subquery return like this:

---Batchnr---
3 B12
4 B13
1 B14
1 B43

and so on..

How do I solve it the best way?