The b9sus is also named suspended fourth flat ninth
Use phryg instead of b9sus
Use 7b9sus instead of b9sus
Use 7b9sus4 instead of b9sus
A b9sus is a Unknown chord
How to construct a b9sus chord?
Use the following intervals in any order to construct this chord. Start on a specific note on which you want to construct this chord from (for instance the note "C") and calculate each interval on top of it. Afterwards, you will be able to play it on your instrument.