Hi Patricia,
Unfortunately, I am afraid that is not a current functionality that would let you inherit the iteration from another project as your example. Base on it, Team ProjectA just can sync the iterations from Sub Parent project2 or Parent Project. But not able from Team Project2 even Sub Parent project1.
The article below outlines this function.
To access the article directly:
Create an Iteration | CA Agile Central Help
I can certainly understand how an improvement of this functionality is beneficial and would like to encourage you to promote this idea in Rally Ideas (https://ideas.rallydev.com) and provide any discussion items that you think might be valuable.
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