I need help to create an filter and hope some of you skilled people can help
me.

I have a list that is used to insert selections in cells. I can add several
selection to each cell, and each selection are separated by comma.
I need an filter (autofilter look-Alike) that utilize the same list in a
dropdown list as filter input.

MyList
txt1
txt2
txt3

Cell C3: txt2,txt3
Cell C4: txt3
Cell C5: txt1,txt2,txt3

Filter "txt2" should give row 3 and 5 as result