Sharing Column Widths Between Multiple WPF Controls

Is there any way of sharing column widths between controls, not just between multiple grids on the same control?

Crude diagram of what I'm trying to get at:

I'm currently messing around with getting the widths of the labels in the first column of each UserControl, but it seems a messy solution that is quite CPU heavy (finding the labels and calculating the widths of the text before it's rendered is nasty!).

I've been reading up on as much about SharedSizeGroups as I can find, but there's nothing suggesting they work across different controls. Is there a simple solution or even a less simple one that isn't utterly hideous?!