can prefect cloud 1.0 display the flow parallelism process in schematic tab?

I think you may want to look at mapping

yes, what I mean is if I use mapping, will schematic display three parallel child flow execution graph?

yup, correct

what can I do to change the wait_for_flow_run and create_flow_run to something more customized?

Here is a discourse document that may be helpful in renaming create_flow_run and wait_for_flow_run: https://discourse.prefect.io/t/how-to-customize-how-the-name-of-a-task-triggering-a-chi[…]-how-to-override-the-default-task-name-create-flow-run/476