Hi Rhys,
There's an embed point in the browse called "Browse Filter".
This happens after the filter is "constructed".
So this is probably the best place to use prop:SqlFilter.
Be aware though that the locator functionality makes use of the filter (and alters it) in the SetView statement. So the + form of the SQL filter is probably gonna work the best for you.
Of course a better approach is to use the SQL () statement inside the regular filter. This would then have the minimum number of side effects.
Cheers
Bruce