I don't know what you intend with either sentence, sorry. I can tell you that they are inscrutable. Perhaps you mean these: 1.
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moon72961. Grandparents take care of their grandchildren.Ah. No, sorry. I can make no sense out of your use of the 2nd 'of' in #2. What kind of transformation do
Then, can I say 'taking care of grandchildren of grandparents' which is intended to have the same meaning from #1?
If it is not correct, I shouldn't apply my knowledge about of like that.