I don't have much experience regarding the subject. So am hesitant.
Eventually, will happen on production.
Is this task something straight forward?
How do you exactly move, export-import? copy-paste? do you have to delete resource on child project afterwards, any document about this?
(I generally make a backup of the entire child project before starting, just in case.)
I use this method almost exclusively rather than having to open the parent project and have two designers open at once. I like to think of it as resource-efficient rather than laziness, but I know which one it really is 
Making a backup of the parent project might also be prudent.
I would also check that no resources of the same name already exist in the parent project. I have totally hosed projects by copy/pasting resources with identical names.
That should already be obvious as an override in the child project.
Ok, SMH... For the record, below are not pass down from parent project to child project:
Yes, page configuration is separate.
Can you help me recall, how to make a project a template? I tried to search Ignition Manual, but did not find.
I think you're talking about a parent project. You just make a project and set that to be the parent of another project. Your child project then inherits all the resources from the parent and can have additional resources that aren't in the parent.
You can't run a parent project and your page configurations have to be set up in the child project.
Oh, I think those are IA created things. I don't use that feature so I'm not certain.
You don't like having multiple designers open simultaneously?
I don't for the same project, but I had 7 open the other day 
