complex macro code to select data based on given conditions

Hi all,

I have a dataset (small dummy included) and what I need is a code which will take from the data only those records that need a service on the specified date and then combine them into batches of 4 to ensure the least possible wastage.

i.e. if 8 machines require service on the date, how is best to batch them (2 batches of 4) for oil refils to minimise wastage.

A further complicating factor is that it would be useful if people could increase the size of the dataset (add new records) as and when needed. If there's a way for the code to include all new records too that'd be great.

I envisage assigning it to a button which can be clicked to run the code.

Any help greatly appreciated!

Thanks,
James