Most basic and foremost thing to do is gradual wean off morning feeds. You can also explain to your toddler why you're weaning him off. Tell your kid that his/her younger sibling needs it more, and as an ate/kuya, he should give way. Toddlers that age can already understand things when explained gently.
To know more about weaning a toddler, you may refer to this link:
http://www.llli.org/faq/weantoddler.html