How can a checkbox append a value to another cell?

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In this example if Cat and Mouse where checked, I would want to append those values to cell E1 and remove them if unchecked while leaving "Checked: " in the cell

First set “Linked cell” for each checkbox

Then use formula

{=TEXTJOIN(", ";1;IF(<range of checkbox values>;<range of texts>;""))}

This is an array formula, it should be entered with the Ctrl + Shift + Enter keys.

See example - CheckedValues.ods