The age differences shouldn't be an issue if the adopted budgies have a sweet temperament.
If you are planning on adopting the 2 budgies, then you will have to quarantine them for a period of about 1 month in a different cage and room away from your current budgie. This is done as a preventative measure to avoid any possible illness to be passed to your budgie.
After quarantine time is over, you can place both cages close by, so that they see, communicate and get used to each other's presence. You can also allow them supervised out of cage time together.
In general, when housing budgies together on the same cage, it's best to keep the numbers even in order to avoid one budgie from being left out.
Depending on the flock dynamics and how they interact, you can choose to cage your younger budgie separately from the older budgies or let them all share a cage together.
If you are given the choice, you can adopt 2 more males instead of a male/female couple or 2 females, as that could potentially be troublesome when sharing the same cage.
Good luck with your decision!