port upgrade outdated order

[René J.V. Bertin]

Hello,

Is there a way to influence the order in which (sub)ports are upgraded?

I'm testing the upgrade of my qt5-mac-devel port from Qt 5.4.0 to 5.4.1, with almost all its subports installed. I've run into an error that can only be explained by an inappropriate upgrading order: qt5-mac-devel-docs complains about mixing library versions. It took me a while to understand, but this error must stem from the fact that qt5-mac-devel-docs is upgraded before some of the other subports. 

What possibilities do I have to postpone the docs subport to after all other installed subports have been upgraded? Is there an accepted/advised naming scheme one can use is the order is strictly determined by port names? (In this case, I cannot simply let the docs subport depend on all other subports, IMHO.)

Reporting this upstream will only lead to another confirmation that one shouldn't build software with a previous version installed...

Thanks,
R.