You have set out your question very well. It seems to me that your 2 year old is seeking attention and wants to be treated like his new baby sibling, waking up for feeds and seeking attention. He was already an independent sleeper prior to tthe arrival of your new baby. He must go back to his room and stay there. Every time he appears he must be led back to his bed. If he starts to cry and perform you will need to apply the controlled crying method[see on Google] this is tough to do but will produce results after one or two nights if you do not give in.
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