Convert Rehearsal Marks (Letters) to numbers

Hi Marc,
it´s been a few weeks and I´m still struggling with the rehearsal marks. I should have initially created them using measure numbers and not letters. However being a relative beginner to score writing I chose letters. Later when I wanted to change to measure numbers in the score this wasn´t recognised in the parts I had created. I tried deleting all rehearsal marks in the score but this had no effect on the parts despite being told otherwise. Would it be possible to re-examine the rehearsal marks for future updates so that they behave logically? For example after deleting the letters I entered numbers but then they were numbered "1" "2" "3" "4" etc instead of
corresponding to the actual measure numbers. The only point in my view in using numbers as rehearsal marks is that they correspond to measure numbers. Or at least there should be an option to choose how rehearsal marks behave. Any change to rehearsal marks in the score should immediately override anything in the parts, even if these parts were created before the score was altered. Again I´m still learning how to write scores effectively and will definitely use measure numbers as rehearsal marks in future. I´m just trying to rescue the layout work I´ve already done in the parts. Any help would be greatly appreciated!