You can merge different categories into 1 startgroup. However, this is only possible for the exact same event.
Athletics.app sees "Shot put 6kg" as a different event than "Shot put 5kg".
To get these categories on 1 Startlist, you can choose to select the general event "Shot Put" (without weight specification) for both categories.
Please note that this will affect the weight shown on the Startlists, see also this question.
It is also often decided to have 2 separate startgroups, so that the correct weight is entered on the jury form. You then receive 2 separate jury forms that the jury completes one after the other. You can set the start and end time of both startgroups to the same time.
This has been automatically translated into English