Conditional grouping

Hi kulkarni21vinee, check this:

Output

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("ZcxLCsIwEAbgq5SsFHoJFSooreJjISWLMQ51SMzIxFi8vbZWSHH7/Y+6Vsf9TOVqUk6zCtvsxGKVzn+8FET/JOcwwULwgkLGhnOUJgm6k8WVDDSc6DyKI9882PdYCHiDQ3sLQqHnFdzBD3pg++KRViDwV9sEsGOtyNrvcBdDIPjQmh3fPIyxW5ccDLdK6zc=", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Country = _t, City = _t]),
    GroupedRows = Table.Group(Source, {"Country"}, {{"T", each 
        [ a = Table.SelectRows(_, (x)=> not Text.StartsWith(x[City], "(M)"))[City], //except Major
          b = Table.SelectRows(_, (x)=> Text.StartsWith(x[City], "(M)"))[City], //Major
          c = Table.SelectRows(Table.FromColumns( {[Country]} & { if List.IsEmpty(a)then b else {Text.Combine(a, ", ")} & b }, type table[Country=text, City=text]), (x)=> x[City] <> null)
        ][c], type table}}),
    CombinedT = Table.Combine(GroupedRows[T])
in
    CombinedT