Interest incurred for an investment in a "passive activity" generally doesn't qualify for the investment interest deduction (a schedule A deduction to the extent there is net investment income). A passive activity is a business or trade in which you hold an ownership interest but in which you don't actually participate. However, you could use the interest to offset income you received from the passive activity.
the only way to get this entered as a passive expense is: 1) if the k-1 has an amount reported on lines 1, 2 or 3 to reduce income by the interest expense or increase the loss. this might result in a notice from the IRS because now the amount reported doesn't agree with the k-1 it got or
2) use a second k-1 same EIN as the k-1 same name (shortened if needed) followed by "related interest exp" this would get enter on the same line 1, 2 or 3 as shown on the actual k-1. make sure to check form 8582 to see that the interest expense shows up.
