Your organizational policy will dictate the response and may be based on the following criteria. Bonus shares would be issued to all in the same proportion based on wider shareholder approval rather than any active choice made by the individual shareholder.
As such, possession or otherwise of UPSI would not be considered a factor and therefore prior approval may not be required.
The aforementioned logic does not apply in the case of rights issuances, since there is an element of active choice in exercising the right. Accordingly, prior approval may be required.