Can you have a model inserted as a mate to a plane?

Try using Mate references 2014 SOLIDWORKS Help - Mate References

One option would be to use Multiple Mate mode.  Insert your components, then activate the Mate command and click here:

Then it will look like the screenshot below.  With the first box highlighted as shown, select your plane.  That will activate the white box.  Select the surfaces of your components that you want coincident to the plane.  They'll be listed in the second box.  When you've finished making your selections click OK as usual.

Edit:  Maybe I misunderstood.  I thought you have multiple parts you want mated to a plane, but after re-reading your question maybe you mean that the components will be used in multiple assemblies mated to the same plane.  If so, then Deepak's answer is the way to go.