I managed to consult a few persons and finally one came up with the correct answer which I felt is quite an insight. TRH actually means Their Royal Highnesses! This is the plural version of HRH (which is more familiar)!
Second item I found out was that the reprinted stamp sheetlets with TRH has only limited release! I tore up the stamps to make my covers! Oops!
So SODA holders, hold on for your orders!
Third item I found out was that the stamps are still available (from the first print minus the emblem with the original text)! Thus the stamps on FDC price will probably stabilise in the market. However the miniature sheet on FDC will probably move up as it is really finished (unless there is another reprint!).
So there you have it. My English lesson for the day!