I am 59 years old. I raised 6 children and now have 4 grandchildren. My first 4 children are boys; the last 2 are girls; all my grandchildren are boys! Here are my suggestions to you: Your son is mimiking the baby. Get him interested in other children his own age; have an exchange "play day" 2 or 3 x a week with a friend. Enroll him in preschool 2 days a week, then 3 days a week. Let him see how "real big brothers" behave (ie, using the potty, washing up, etc.) Also, take advantage of a "Mom's Morning Out." We have one at our chuch in Colts Neck. You drop your cherrub(s) off and take some time for yourself. (See the info at http://www.coltsneckbaptistchurch.org/ Scroll down to "Mom's Morning Out" in the center of the page and click on the link for more information.) When you leave your youngest with trusted folks, you can spend some quality time with your son, doing big-boy things that require using the potty if he wants to do big-boy things with Mom (taking the focus off baby and putting it on him). It will all work out, provided he absolutely does not have any medical problems, or there are no traumatic emotional problems associated with him using a potty that is child-sized. Don't expect him to feel comfortable on the "big" potty. Sometimes that scares children, especially if they've had an experience of almost falling in. Also, the flushing noise may frighten him: he sees his "prizes" going down the dark hole and it may be a fearful picture for him to cope with. Children cannot express their fears so we can only imagine and guess what they might be; and we don't always know "why!" So, I strongly suggest you get your son involved on a regular basis with other children his age. If there are no serious problems with him, then the "pooping in the potty" will soon become the norm again. Above all, pray for guidance. I hope these suggestions help. ~EL