Hello Sarlinda!
Allow me to give you some suggestion :)
Today, manage the child foods to keep healthy certain have some difficulties.
this sentences do not relate with the prompt. It will better if you explain you last sentence before this sentence.
... control the child foods by giving attention
to children's favorite food.
In additionally, the parents can ...
Additionally -> adverb
Addition -> Noun
In addition or additionally
By this way, the child can ...
It is just a suggestion for you for a better sentence structure.
By this way, the child can save their
pocket money
by do not buy unhealthy snack outside parent's guide
Hope it helps you :)