Upgrade while less than 3 months on current version of Avast 4.7?

How can I upgrade to the Family Plan (3 years coverage option) from Avast 4.7 (build December 2007 - 1098)? I would like to reduce my cost of this upgrade since I just purchased Avast! and now my wife wants it on her PC, too. Is there a way to get the Family plan and not feel I’ve wasted the money spent for the version I am currently using?

If this post is not the ‘correct’ means of asking this question, can someone suggest how to ask appropriately? I simply wish to get more coverage, to include my wife’s PC, and don’t want to spend full price for the Family Plan without receiving credit for the remainder of the year I purchased (9 months still to go).

You may be best contacting sales @ avast.com (without the spaces) directly.