Add exposition to selection

[NathanOtano]

For a lot of comands i really need an "add exposition to selection" shortcut.

If i want a comand i always have to create two comands : one to act on a whole selection of frames and one to act only on the instance where the cursor is. So in the second case i have to select the instance, on the first case it acts on the already selected frames. If i can add the current instance to the selection everything will work fine.
for the case when we add the exposure to a selection that is no next to the instance, it may act just like when we press maj and select all the frames between.

Also i often need to go to the end or beginning of a selection without losing this selection.

Can it be possible?

Nathan