There's another way and others will have other ideas, but here's what I think might be the simplest.
In your process, you might have a "main instance" flowing through it (the one single approval you're looking for). You could then have a Parallel-Complex gateway with two branches. One branch would go to an interactive activity where someone could do the single approval. The other branch would go to an embedded subprocess set up as multi-instance. The collection passed into the subprocess would create an instance for each item in the collection. Both the interactive activity and the embedded subprocess would have a sequence flow going into the Complex merge gateway. If the sequence flow coming from the embedded subprocess is taken (meaning that all of the items had been approved individually), then the "main" instance in the other branch would be aborted and the instance would leave the complex gateway. If on the otherhand, the instance in the "main" interactive activity had been approved, then the instances in the multi-instance subprocess would be aborted and the instance would leave the complex gateway.
My requirement is,if user1(initiator) submits the multiples requests from BPM workspace(lets take 3 requests),then user2(Approver) needs to get single request(Consolidation of 3 requests from user1).Then user2 will approve the single request(Consolidated request).Could you please suggest us to achive this.