You say that your oud pegs are of different length.
The length of the peg is determined by the thickness of the string and the distance between the nut and the bridge of the oud. Thicker strings require longer pegs to provide enough space for winding and adjusting the tension, while thinner strings can use shorter pegs.
It is important to use the correct length peg for each string to ensure that the string is properly secured and can be tuned accurately. Using a peg that is too short or too long can cause the string to slip or not hold tension properly, resulting in an out-of-tune instrument.
Since the bridge is fixed, you can remove all the strings for a short period of time, but restring and retension as soon as you can.