Help required in Planning a trip along with person of reduced mobility

Dear Members,

My family is coming to Brussels to meet and stay with us for few days.
My younger brother(28 years) is patient of Celebral Palsy and cannot stand up/walk and also is sub normal. He remains on wheel chair always.Its my wish to show him places and he is excited too.

I am thinking of planning a trip to Kuekenhoff gardens from Brussels with my family. This would be first trip outside Brussels so need your guidance .

We total would be 6 adults and 1 infant.

What will be the easiest mode of conveyance from Brussels to Kuekenhoff garden for us. It should not be heavy for pocket.
And any other point which i should remember(according European laws) along with handicap person while travelling.

Kindly suggest.

For further trips, i would be taking suggestions and then finalize the places which i can show them.