Populating 1 listbox on the basis of another listbox selections

Hello everyone,
I need some help regarding append.
Actually what i wanted to do is, ihave some listboxes and on the basis of values selected in 1 listbox , I want to populate another listbox, I took all the values selected by the user in a string seperated by commas then I used a split function to get all the comma seperated words in another string without commas.
Now i want to filter some data on the basis of these words and populate another listbox, so I am doing this :

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what i want is how can i add filters dynamically on the basis of no. of words in that string?
Please help me guys, if you know how to do this or any other approach of doing the same.

Thanks you.

Thanks for replying Snb.
Can you please elaborate your code, I am getting what it do?
Its running and filtering the source sheet only and that too with a different value, which i have not even selected.
I am selecting values from the listbox named lstSpecialization and wants to populate Listbox1 with the matching values of the selected values of lstSpecialization. Its damn complicated for me .
Please help