Adding coded response options to text questions?

Hi Qualtrics Community! Is it possible to add coded response options to text entry questions? For example: MOMAGE "How old is your biological mother as of today?" _______ years old [numeric entry, 0 - 200] 998: "Don't know" 999: "Prefer not to answer" The 998 and 999 response above would be the checkbox for 'Don't know' and refusal respectively. The only solution I've seen so far is to add a new variable below a text entry variable.