Group by running totals with reset

### Sample Data ### Expected Data Need to append trades under an order in a record, was able to do that using string_agg, now I need to split the orders with a maximum value of 10. That is, the quantity for the single order should not exceed 10 , need to combine trades under a single order as much as possible as fewer amended orders are desirable. For example: I can combine tradeid 11 and 12, the running total is 9 but when I combine tradeid 13 it becomes 12 (exceeds 10) so that needs to be in a separate order. Am aiming to rank the trades so that I can group by orderid and rank to get the result. Using SQL Server 2016. Script to create the sample table.

create table #order
(
orderid varchar(100),
tradeid varchar(100),
quantity  int
)

insert into #order (orderid, tradeid, quantity)
values 
('a',    'a1',    5),
('a',    'a2',    4),
('a',    'a3',    3),
('a',    'a4',    12),
('b',    'b1',    9),
('b',    'b2',    8),
('b',    'b3',    7)

### Second example

INSERT INTO @Test 
    (OrderID, TradeID, Qty)
VALUES ('a', 11, 5)
    , ('a', 12, 4)
    , ('a', 13, 3)
    , ('a', 14, 5)
    , ('a', 15, 1)
    , ('b', 21, 9)
    , ('b', 22, 8)
    , ('b', 23, 7)

### Expected Result In reality, the maximum would be about 1000 orders at 10 trades per order. A good approximate solution should be good enough.