Looking for a single text value and returning 1 or multiple text values in one cell

Hello,
As suggested by Azumi this problem can probably be solved by a macro or a VBA code. Hope someone can help me with my following problem.
I want to lookup a certain text value from a worksheet (sheet 2 in example file) and find this exact text value in worksheet 1 column A. Then the result must be the corresponding text value (or values!!) from sheet 1 column C. I want the result in a single cell next to the lookup value (sheet 2).

See attached file DemoMarc3.
For example: if I lookup "Hello" the result must be: "Amsterdam". But when I Lookup "Hay" the result must be: "New York, Berlin". And when I lookup "Good Morning" the result must be: "Madrid, Madras, Amsterdam, New York". The number of empty cells between the text that I want to find in column A and the next text in column A is not a constant and will vary.
Thanks so much for all your help.
Marc