Isaac Harlan b abt 1798

I am actually researching the McBride family, I have found my ggg grandfather on the 1860 US Federal Census (TN) living with the Isaac Harlan family. Household members:
Isaac Harlanage 62
Harriet T. Harlanage 28
Artimesia Harlanage 25
Isaac J. Harlanage 19
Lesson B. McBrideage 15
Lucretia B. Mcbride age 9


Does anyone have any info as to why these two McBrides were living with the Harlans as youngsters, and who their parents might have been? Thanks for any help!
/Faith
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