You can add multiple staff to a shift using the advanced edit mode, this article has more on accessing advanced edit mode, if you already know this you can skip to the section titled "Add staff".
Adding 2 charges to a shift to charge twice at a the 1:1 rate
NDIS doesn't allow you to charge a single line above the price limits, so in order to charge 2:1 you need to charge 2 x 1:1 by splitting the invoicing.
Using advanced edit mode to split the time of the client - set both time splits to the full length of the shift.
The resulting invoice will have 2 line items for the same time and duration.
In this case 1 - 3:30 pm Personal Care will display twice on the invoice for this shift at $55 per hour.