Install on both phones & choose roles
Rupix Guardian is one app with two clearly separated experiences. Install it on your phone and your child's. When you open it, it asks "Who is using this device?" — choose Parent Device on yours and Child Device on theirs. The role sticks to that physical phone, so a parent's session can never end up driving the child's app (or vice versa).
Screenshot: 01-role-selection.png
Role selection screen showing 'Who is using this device?' with Parent Device and Child Device cards