Default Sidebar widget?

Hey guys!

Well, my question now is quite simple... Is there a way to set one default sidebar widget?

I mean, the default sidebar widget I want to set out is the Join My Multisite widget, so users across de network can choose to be user of that blog, but I'm afraid that a lot of admins will forget to insert this widget on the sidebar, so, I network activated this plugin, and I want to set it's widget as a default widget that can not be turned off or took of.
Is there a way to do that?

Thanks

Derek