Expression help

A while back, I created a profile grid block to be inserted into paperspace. The idea is that I can use it to display the grid on plan and profile sheets instead of the Civil 3D profile grid. It looks cleaner and it generally gives me a little more control.

I sort of automated the station and elevation counting by creating two table entities, one for the datum station and one for the datum elevation and then the rest are a series of fields that count upwards from those number strings in pre-defined increments. It works, but it's fairly crude and it means that I have bedit the block every time I need to change the station and elevation, which is a messy and time-consuming affair. I have attached the current block for reference.

What I really want to do is just be able to double-click the block, edit an attribute and have all of my numbers update from there.

I'm thinking that maybe creating user variables with the parameters manager would somehow help, but I'm not sure. What I need is an object that I can edit from outside the block (like a user variable or an attribute) and then a series of fields which contain an expression (diesel maybe?) that take the number string given to that attribute/variable and add to it incrementally.

If anyone can give me any pointers as to how to accomplish this (either the expression or how to apply it in the block), I would be eternally grateful.

Thanks!

C-PROF-GRID-BLCK.dwg