Hi Claire,
I'm still trying to wrap my head around the online search tool but here's what I found

Also, I don't know what's up with the formatting...sorry.
Plain fat free is free for all brands
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[TD]Activia Light Fat Free Greek Yogurt, all fruit flavors, 3½oz [/TD]
[TD="class: greenSyn"] Free[/TD]
[TD="class: addSynsToDiary"][/TD]
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[TR]
[TD="class: synResultTextStyle"] Activia Light Fat Free Greek Yogurt, Vanilla, 3½oz[/TD]
[TD="class: greenSyn"] Free[/TD]
[TD="class: addSynsToDiary"][TABLE]
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[TD="class: addSynsToDiary"][/TD]
[/TR]
[/TABLE]
[/TD]
[/TR]
[/TABLE]
[TABLE]
[TR]
[TD]Activia Stonyfield Organic Smooth & Creamy Yogurts, all varieties, 4oz pot
[/TD]
[TD="class: greenSyn"] 1½ [/TD]
[TD="class: addSynsToDiary"][/TD]
[/TR]
[/TABLE]
Yoplait - Greek 100 Calories Yogurt, all varieties, 5.3oz pot 1/2