First, there's no January Use Year so nobody would ever have any points that expire Dec 31st.
Now, when MS makes transfers a number of things can happen. Technically transferred points are suppose to retain their original use year and original home resort. But this doesn't really happen as the computer systems have to assign points to one of your existing accounts. If you only own BWV and someone transfers OKW points to you, they currently wind up in your BWV account since you don't have an OKW account. Currently
DVC does not have any way to temporarily create 'sub accounts' such as creating a temporary OKW sub-account for you to hold those transferred OKW points.
Most likely the points will transfer into your BWV June UY. In this case the points are absolutely no different than your regular BWV points so there's no reason to do anything. You can bank those points just like any of your other points. There is no reallocation of points on your reservation necessary.
If you own any other resorts, the transferred points may go there. Suppose you also own OKW. If the points being transferred are from an OKW owner they will go into your OKW account. If they are coming from a BWV owner, they will go into your BWV account. If they come from anyone else they might go into either, but you can decide which one.
Finally Use Year can be different as transferred points can actually change use years. You have a June UY so next year beginning 6/1 you will be in your 2006 UY. Suppose you find someone with a Dec UY and in Nov 2006 have them transfer points to you. But in Nov 2006 that Dec UY owner is still in their 2005 UY, since their 2006 UY won't begin until 12/1/06. In this case they are still 2005 points but will transfer into your June 2006 UY since your June 2005 UY has already passed.
There is one caveat: DVC is working to have transferred points retain their original home resort and use year month. If they get that system up and working, then any transferred points coming from a non BWV owner would retain their original resort and would be subject to all the same rules as if you owned those points under that home resort. For example, if today you own BWV and OKW points, you cannot make a reservation at 11-months using BWV points for a BWV stay, and at 7-months 'reallocate' the OKW points to that reservation since that would be trying to circumnavigate the 11/7 month windows. In this case, to reallocate points requires a cancellation and making a new reservation. The new reservation is subject to availability, with anyone on a wait list getting the reservation first.
Hope this helps