Max Value per Order based on two columns

Hi,

I am not sure if I understood correctly but here is a commented PQ that might be of use.

Start data:

PQ:
let
Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMjQwUNKBkhbGBkqxOqhilnAxIyDPGCwGEzEGsk1gIrEA", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [#"Order Number" = _t, C1 = _t, C2 = _t]),
#"Changed Type" = Table.TransformColumnTypes(Source,{{"Order Number", Int64.Type}, {"C1", Int64.Type}, {"C2", Int64.Type}}),
#"Added Custom" = Table.AddColumn(#"Changed Type", "Value", each List.Max({[C1],[C2]})), //Here we get the max of columns1 and 2
#"Grouped Rows" = Table.Group(#"Added Custom", {"Order Number"}, {{"Value", each List.Sum([Value]), type nullable number}}) //Here we group the values based on order
in
#"Grouped Rows"

I hope this helps and if it does consider accepting this as a solution!