There are 3 different IDs that come with Givalanche gifts. 

Let's say Constituent A gave a one-time donation on a form with Givalanche enabled. 
This gift will have a Givalanche ID for A. It will not have a Parent or Root ID.

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Let's say Constituent A shares their Givalanche link with Constituent B.
Constituent B donates using Constituent A's link. Once this donation is processed in the Raiser's Edge, this gift will have a Givalanche ID, a Parent ID and a Root ID. 
    The Givalanche ID will be new and specific to Constituent B.
    The Parent ID is the Givalanche ID of the person direct above them (the link they clicked). 
    The Root ID will match the Givalanche ID of the originator.

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If Constituent B shares their Givalanche link with Constituent C
  The Givalanche ID will be new and specific to Constituent C
  The Parent ID is the Givalanche ID of the person who shared the link to them: Constituent B
  The Root ID will match the Givalanche ID of the originator: Constituent A.

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Ultimately, the Givalanche ID matches whoever the donor is and the Root ID is always the originator. The parent is just the person directly above.