We prefer not to promote ideas to features, but rather link them so that we have more control over the status and the maintenance of history. It is important to me that I be able to see the number of aggregated votes from any linked ideas on the feature to aid in prioritization. My workaround will be to type this in manually at a point in time, but I will lose the ability to see votes accumulate.
I sorely miss this functionality as well - when it is time to weigh two features, one aspect I am looking at is how many people are asking for this. With multiple ideas being promoted to a single feature, Aha is already doing a part of this feature where under the related tab it says "This feature has a total of 14 votes from 3 ideas" - the ask is to simply make it a field on the feature.