Hello and Thank You for responding. Your son is acting out because he wants your attention especially now that you are working in the summer months. He does not yet have all of the verbal skills to explain his feelings and therefore he acts out toward you and sometimes with his sister. He misses you while you are away at work even though he seems to be fine with the childminder. He acts worse in the morning because he feels like you will soon be abandoning him as he goes to the childminder.
I am not sure if he just turned 2 or is closer to 3. But anyway, you must start each day out telling him what you expect. Or you can discuss it in the evening before he goes to sleep at night. Your goal is to improve his behavior to be more positive. Therefore, you can use a daily sticker chart. It would look something like this:
Sunday Monday Tuesday Wednesday Thursday Friday Saturday
Every time he behaves well for a certain time period, he will receive a sticker. Let's say on Sunday Morning, he behaved really well with no behavior flareups. Then he would receive a sticker for that time period. If Sunday afternoon he had some problems with whining, he would not receive anything. If on Sunday night, he had a great night, he would receive another sticker. Make sure that they are stickers of child friendly characters or things that he really likes. Then after every 10 stickers, her receives a special treat, activity, or outing. As his behavior improves, change the number of stickers to 15 and then later on 20. You need to place the sticker chart in a place where everybody can see it, especially your son.
The goal is to make him understand that he is responsible for his own behavior. When he does still misbehave, tell him what you would have liked him to do instead of the negative choice that he made. Make sure he understands what to do the next time. The key is consistency. It will not happen overnight. It make take about 2 months until you see big changes.
Also, try to spend as much quality time with him alone as you can. Read a book. Crawl around on the floor and pretend you are animals. Go to the park. Build with toddler blocks. Finger paint. Paint with water and brushes on the sidewalk.
Good luck to you and have a great day.