Problem 1: Multiple Wikis need to be merged into a single one.
Problem 2: One or more Wikis need to be moved into a Community
Solution with HCL Conmnections provided tools
HCL Connections does not provide any tools for moving / merging / copying Wikis. You need to write your own code that either modifies the relevant tables of the WIKIS database directly, or which uses the REST API to create the new Wiki.
Solution with Connections Administration Toolkit (CAT)
Navigate to Content And Access – Wikis. There, you can create a list which contains all Wikis that are part of the merge / copy operation