The Cat in the Hat should be invited back for one more day of fun because the kids will will probably enjoy just as much as the first time. But to put this into contact please refer to "explanation".
Explanation: Many years to come they will have time to have reflected on the things that were not so good to do. They might will have gained enough insight (hopefully) over the years as to what to refrain from and what could bring about a healthier outcome of "fun". But in the end, what they will have are long lasting memories with that Cat in the Hat!!!
“whose father worked for the railroad” is a subordinate clause as it is a relative clause beginning with the pronoun “whose”. It is particularly used in written English and it refers to possession of things or to make association or connections with other things or people.