Dear J.,
Whining is normal, you are giving her plenty of attention, and she doesn't need a bro or sis , at least not right now. The only way to stop the whining is to stop paying any attention to it. Act like you do not hear it. Do not respond in anyway, especially do not reward her if she is whining. They eventually stop, especially when you do not give in to whatever it is that they are whining about. This is simple, but important, you are in the process of establishing your 'rules' for her, and you need to be consistent - both you and Dad. The whining is an attempt to control you, so don't let that happen. You will be extremely sorry if you do, believe me. Please. Just be sure to watch that she is o.k. while you are 'ignoring' her.
One thing that you could do is give her something that you think my interest her just before you quit the attention time. Otherwise, just be patient, and know that you are doing the right thing. O.K.?
Relatives want to help, but they aren't right in this situation. Sincerely, C. N.