Parent/Child Routing Method
Selecting this method for a tank will make said tank a "Child" and prompt you to select a "Parent" tank within Lynx. The parent/child relationship within Lynx is fairly simple: the child tank inherits the parent's return date.
This means, regardless of the routing method used by the parent tank, if the parent tank's return date is 01/01/01, the child's return date will be 01/01/01. Putting the tanks on the same route ensures if the parent tank is receiving a delivery, the child will as well.
This can be helpful when you have a customer with multiple tanks that are not manifolded. By setting one tank to be all of the other tanks' parent, you can just worry about that one parent tank's routing method/return date and know that all tanks will be delivered to on the same day. Or, if Customer_A has a tank located near Customer_B, you can set Customer_B's tank to be the parent of Customer_A's to ensure that if you are making a delivery out to Customer_B you will fill/check Customer_A's as well (assuming they're on the same route).
If you're unsure on how to change the routing method for a tank, see CHANGE THE ROUTING METHOD USED FOR A TANK.
How to select a tank's parent:
1. When you change a tank's routing method to Parent/Child, a new "Choose Parent" dropdown menu will appear like so:
2. Left-clicking on the dropdown menu will open up a window for you to select the parent tank like so.
For an example of this, click here.
3. You can also search for the tank's account# using the search box at the top
4. To change the search method, choose a different option from the dropdown menu below
5. Choose the tank by either double-clicking it, or left-clicking it and then left-clicking on 
Here are some examples of when to use Parent/Child:
Example 1Parent/Child Example 1
In this example, the customer account has 3 tanks. They're all on the same route, and they all have different return dates.
Making one tank the parent of both of the others ensures if we deliver to one tank, we deliver to them all.
BEFORE
Refreshing the return date only changes the return date of the selected tank.
AFTER
Refreshing the return date changes the return date of the selected tank, and since that tank is the parent of both of the other tanks, their return date gets changed as well. You can also see the "Parent Tank" field has the serial of the parent tank.
Example 2
Parent/Child Example 2
In this example, let's assume Nicolas Bourbaki lives very close to John Doe and we want to set it up so that if we're going to make a delivery to Mr. Doe we should check/fill Mr. Bourbaki's as well (please note, the tanks are on different routes in this example, normally they should the same).
Here's what we did:
1. Set Mr.Bourbaki's tank to be the child of Mr.Doe's tank.
2. Refreshed the return date on Mr. Doe's tank.
3. Verified Mr.Bourbaki's return dates changed.