There is a limit of 8 siblings and 8 additional household members that you can add in the application using the blue "Add Sibling" or "Add Household Member" links on your Household page. If you have more than 8 siblings, prioritize younger siblings who would be in your Primary or Non-custodial Household(s), and leave out siblings in Independent/Other Households. If you have more than 8 additional household members to add, prioritize those in your Primary Household.
You should then use the additional information box on the Household Confirmation page to provide information about additional siblings or household members. Include the full name and age of each sibling/household member, and any other relevant context. Please also confirm what the correct Primary and/or Non-Custodial Household Size(s) should be based on additional siblings and/or household members, since you will be unable to manually edit the Household Size(s) given on the page.