Is it possible to limit users use of widgets?

Hey,

I'm using Blog Template plugin, which is great, and i can build a custom sidebars for all new sites on my network, the problem is when a user creates a new site, he can remove widgets from the sidebar. Is there a way to restrict a user (admin on his own site) from removing specific widgets from the sidebar?

For example, i have a plugin that shows all new posts from all across the network on all sidebars, but i don't want the user admin to remove that widget, but i do want to let him the options to add other widgets available for him.

Is there a way to do that?

Thank you