Email Merge with variable merge records break by client level

Dear All,

I would like to send email with the email merge function in word. My data is in invoice level, however, I would like to send out the emai merge break by client level (client **), which 1 customer will only receive 1 email show all the invoice record of the customer.

I have an option that to tranpose the data into client level. However, as the no. of invoice of each customers is not unique, the final output will have many empty space if i use tranposing the data.

Therefore, I would like to seek for your help to see if an alternative. As I am not familize with VBA/Macro, therefore, I am welcome to have the solution without touching the VBA/Macro function. Of course, if it is not an option, I am willing to learn the solution in VBA/Macro function.