KNIME 5.7: Use of container output in another flow

Hi,

I have a flow, flow A, that writes data to a Container Output (Table), which I want to use as starting point for another flow. In that flow I use the Call Workflow (Table based) node to load the data. When I configure, I can select flow A and then choose the Container Output in the field “Fill output table from”. I can however not run this node (red). As this second flow was (by default) created as a separate project, that can be the reason. AI said I have to create a workflow group and put both flows in it. I should be able to create a workflow group by rightclicking on my workspace or folder. However, this option does not seem to exist. Someone knows how to create a workflow group or solve the sharing issue so that I can keep the flows manageable?