You can use a helper column to accomplish that like this:
| A | B | C | D | E | F | G |
---|
Name | Type | List | Select | | | | |
Amy | Parent | Bob | | | | | |
Bob | Child | Cyndi | | | | | |
Cyndi | Child | Doug | | | | | |
Doug | Child | Gayle | | | | | |
Elayne | Parent | | | | | | |
Frank | Parent | | | | | | |
Gayle | Child | | | | | | |
| | | | | | | |
| | | | | | | |
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INDEX($A$2:$A$10,SMALL(IF($B$2:$B$10="Child",ROW($B$2:$B$10)-ROW($B$2)+1),ROWS($E$2:$E2))),"")}[/TD]
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Your list is in A:B. Then I created a formula to pull out the "child" names in column E. Put the formula in E2, confirm with Control+Shift+Enter, then drag down the column. Finally, in G2 I created a Data Validation rule. Click on the cell, on the Data tab click Data Validation, click List in the Allow box, and put this formula in the Formula box:
=OFFSET($E$2,0,0,SUM(IF($E$2:$E$10<>"",1)))
Change the ranges in both formulas to match your sheet. Let us know if this is what you're looking for.