Hi there! vSphere Replication does not support changes on the replicated VM. The only way to achieve this is by changing the source VM resources, which I believe it is not what you need.
What do you mean by "connect all the VMs"? I you don't have enough resources to power on the VMs, i suggest you change the VM resources before powering on manually. Take in consideration that some applications and operating systems are sensitive to this changes and it may cause you some licensing problems, for example.
Powered Off VMs only consume storage resources so when you need to power on the replica, you can manually change the resources before yo turn it on.
Regards!