To create a group for a main product which has batches on mobile, please refer to the below mentioned steps:
Step 1: Navigate to Product >> Click on Three dots >> Click on Create group
Step 2: Select the Main Product >> Click on the Batch Product that you want to add as main product. Refer to the below shared article for adding the batch product.
Step 3: Select the Sub Product and enter the desired Quantity that will be used in making the main product and Click on Continue.
Step 4: Confirm the Sub Product and its quantity >> Click on Create Group.
Step 5: Now the group has been created and you can click on the product and stock in the product by selecting the desired batch
To stock in a batch product, refer to the below shared article