Does a grant deed allow the seller to issue a percentage of interest to the buyer?

If I understand your question correctly, the owner of a property may transfer any portion up to and including 100% of what they own to another party. Why would they be restricted in how much they can transfer [in India, there may be such restriction to prevent farm land from being divided into such small parcels as to make it much less efficient to use to grow crops, but that would only occur by governmental order].