Can the invesment plan be assigned to more than one child?
Investments if done based on one ownership as a parent, can be meant for multiple children.
What if my children are adopted or unrelated to me biologically?
The same applies to any child, if we want to be responsible to plan for them.
At which age is it best to start investment for my child?
The earliest to do is as soon as you have the intention to start saving up for their education. The longer the horizon towards Pre-university age, the better.