Dear Washington, D.C. Tenant:
I am an attorney licensed to practice law in New York. I do not practice law in the District of Columbia.
Because you may be concerned that no attorney took a look at your question, I want you to know, that may not be so.
You may or may not have a claim for the value of the walker and so you could try to resolve this matter in Small Claims Court. You should also look to your lease and to the rules and regulations to see if there is any disclaimer by the landlord of liability for loss to a tenant's personal property unless the loss was caused by the gross negligence of the landlord, and if there is a prohibition on placing items of personal property on the balconies. You should also look to see if the lease required that you have your own insurance to protect your possessions in case of loss.
Your real claim is against the tenant who injured and damaged your daughter's walker because she is the person who performed the act of pouring something over the balcony. So if you sue in Small Claims Court you may think of including the one responsible for your loss as well.
As far as a reason why your question was missed along the way: Your question may have "aged out" of the most recent questions posted and the longer the time the question is not answered the further it moves away from the newest and most recent questions; sometimes a question posted in AVVO does not lead to an answer that may solve your problem or direct you to a solution; lawyers when answering online questions where no lawyer and client relation may exist may be shy sometime to propose an answer that may be construed as legal advice. When I look to the older unanswered questions, even when not in my state, I try to put information where you may find a source to help yourself, and I will always suggest that you seek local counsel as well.
You may try again and redraft the question. It is possible that your question is not clear for an attorney to answer.
The answer provided to you is in the nature of general information. The general proposition being that you should try to avoid a bad outcome if you can.