How do I add an abbreviated word as an exception in segmentation rules?

Dear Studio 2015 users,

One repetitive word that appears in all of the files in my project is incorrectly segmented because it's abbreviated with a period. ("Prop." is the word.)  Can anyone show me how to add this word as an exception in segmentation rules?  Alternatively, if there is a more efficient way in handling this, I would love to know!  I think any method would be better than trying to merge two segments manually in Studio.

Thank you so much for your help!

Chunyi