That's a wrong framework to use. Parent/child relationship is a special case of dependencies between tasks, which can be more generally modeled as start/finish relationships, i.e. one of: Start-to-Start, Start-to-Finish, Finish-to-Start and Finish-to-Finish; parent-child relationship is Finish-to-Finish here. This distinction starts to matter if you want to plan out more work items than you can quickly eyeball on a Kanban board, and it's all well-trodden ground with nearly century worth of prior art, to which our entire industry is entirely oblivious.

Useful search terms: PERT, Gantt charts, critical path, PMBOK.

Popular software occasionally spotted in use in our industry (usually by PMs, in secret) that supports it: MS Project, maybe Jira, ... is there anything else?