CSS requiring information about sibling's college even though we don't know yet?

For filling out the CSS form there under the Dependent Education Expenses section of the application it asks all the college information about all siblings. I have an eldest sibling and a twin. The eldest we were able to fill out for because they are in college, but my twin is applying for class of 2024 like me. Should we estimate the values and names? The questions are:
Name of the college or university attending
Total cost to attend this school
Total educational expenses paid or expected to be paid by student’s parent(s)
Attend full-time or half-time? *
Type of college*
It appears that only the last two are really needed (indicated by the stars), but what if we don’t know if they are going to attend a private or public college?
Thank you all, I hope you can help me because the answers on other posts have been mixed and I haven’t found a straight forward answer.

the only answer you have now is “TBD”

As I remember, the CSS has room to add additional information and explanations for “Special Circumstances”

You can detail the issue in the “Other” tab under Special Circumstances.

You can also contact the CSS directly, by phone or email.

Finally, as the CSS only collects data that is sent on to the Colleges that make the actual fin aid determinations, it would be a good idea to contact the individual college fin aid departments directly to discuss.

Thank you so much, I’ll try reaching out to who I can then!

I asked this question a couple of months ago and the consensus seemed to be put an anticipated cost. I used $60,000, which I thought would be the worst case scenario (no merit or FA at the higher but not highest priced schools on their lists). Some schools will request final costs at a later date but some do not.