Where to I enter info for a second home that is co-owned with siblings

[erlinaklewis]

information like taxes and updates, this is not a rental home

[Mr. Terry L]

Not sure what you mean by "updates".  If you mean improvements, then you keep track of them for when you sale the property as they would adjust the basis (since this is not rental).  As far as the taxes, they go on schedule A under "Taxes paid" just like your primary residence.