Chose service quantity before you chose date and time

Hi

Is there any chance to force the customer to choose service quantity before you choosing date and time? Or make quantity possible to change even after date and time was chosen? or make default quantity as 0 to force them to select it? I have a problem when customers (for example) they want service quantity more than 1 (which is selected always 1 default) – but first they chose date and time – then appointment highlights straight away underneath the calendar and is counted only as quantity 1 and then they change the quantity – it doesn’t count, once they submit – it’s still 1. They would have to cancel the appointment, change quantity first and then pick a date and time – this way it works and count quantity.

Thank you in advance !!