Hi, I bought some red and black currant bushes in the spring. They all had some berries already.

The problem is that the bushes only have one trunk and all the brunches grow from the central trunk. How do I prune my currants to multiply the trunk - to make it look like a bush? Are there any special techniques? I am concerned that the branches will start falling because the bush will just become unstable as all th branches just grow from one trunk/stem? Sorry, I rambled a lot, just not sure how to explain. Thanks!