Some cloud applications need a scalable resource group with the added ability to specify the exact resources to add or remove from the group

Some cloud applications need a new resource group with the following characteristics:
1) Create an initial number of identically configured nested resources.
2) Identify resources within the group using the index with the ability to specify a variable to be replaced by the index.
3) Add/Remove specific resource within the group by specifying the indices of involved resources.
4) Grow/shrink the group size (with a certain increment) when user defined triggers are met.