I read through your later posts and agree that the FLP must have a business purpose even if that business purpose is to earn rental income, interest, dividends, and capital gains.
However, I disagree with you that a creditor can take any assets of a limited partner. The creditor cannot take anything out of the partnership nor can he step in with any controling powers. If the creditor wins, he only wins the right to any distributions out of the FLP. In the case where the FLP is in the business of earning investment income, that creditor would not be able to liquidate any of the partnership assets but would have to pay taxes on phantom income generated by the partnership.
I am basing this on the provisions of the Uniform Limited Partnership Act that is recognized in every state as far as I know.
The Uniform Limited Partnership Act provides that a creditor cannot take assets of a limited partnership to satisfy the debt of a limited partner. Basically, the partnership isn't liable for the debts of the limited partners. It also provides that a creditor of a limited partner can "charge" that partner's interest to pay a judgement, and that the creditor will be treated like an assignee of the partnership interest. This does not mean that a creditor cannot take a limited partner's interest in the partnership to satisfy that partner's debt.
Some states do, however, limit the ability of the creditor to "take" the partner's interest. This is where your charging order comes in. The creditor will get an order of the court requiring any distributions to the partner be paid to the creditor. The creditor just sits and waits or settles with the debtor or other partners.
However, the trend is to allow the liquidation of partnership interests where the creditors judgment cannot be satisfied by the charging order. Because of this trend and the fact you can't be sure where you will get sued and what state's law applies, there is always the risk that a creditor or bankruptcy trustee will successfully obtain ownership of the limited partner interest.
The practical problem still remains, however. Even if the creditor gets ownership of the limited partnership interest, it is going to be hard to force a distribution. There also is the tax risk you mentioned, but I believe all the LPs will suffer the same consequence. Nevertheless, a determined creditor or trustee will likely be able to squeeze something out of the partnership interest.
It is worse for the debtor if the debtor is both the general partner and a limited partner. Say dad sets up a FLP. Dad is the GP and is a LP along with his kids. Dad ends up in financial trouble and files bankruptcy. As trustee, I would step into his shoes as GP and force a distribution to the LPS.
To protect himself, Dad might have formed a LLC to hold the general partner interest. This makes my job tougher but not neccessarily impossible. Dad files bankruptcy. His LLC is property of the bankruptcy estate. As trustee, I take action as the member of the LLC to cause the LLC to cause the GP to order a distribution to the LPs. It starts getting hard if the LLC has a number of members.
Martha