You need to enter just your share of the purchase price and prior depreciation. Ownership percentages do not apply to the depreciation section.

If you indicated your ownership is 50% in the beginning of the rental section, 50% will be applied to all of the expenses like mortgage interest, insurance, etc. That does not apply to assets and depreciation.

See the image below for an example.

I will suggest the percentage to apply the depreciation to make it easier for the user. Thanks

Just report your share of the asset.  For example, if the asset has a value of $20,000, just enter your share ($10,000 if you have just one other owner).  It is much easier.

@Sing8