First, since you`re a partnership you will need to file Form 1065, as you indicated. Since you sister is also a partner, then 1% (her share of the partnership) of the loss for 2007 will be flowing to her. Thus, she will receive a K-1 from the partnership, which she will need to report on her Schedule E of her Form 1040.
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Gina L. Gwozdz, CPA
http://GLGcpa.com
http://TaxTreasures.com