My only problem with Pat's first solution is that when I have let's say 25 lines, the last 5 lines go to the next page which is good. But on that next page, there's not enough data to fill the whole page. So, all the sums goes up to the middle of the page.
But I've made a solution that is working right now. Here it goes if you want to know it:
1- I create a table with all the records I need to put on the bills and I add one column, Group, which I will use later.
2- I use some code to run through the table and insert blank field to make it a multiple of 20. Ex.: If I have 6 lines, I'll insert 14. If I have 26, I'll insert 14.
3- With some more code, I reopen the table from 2 and I assign a group number based on the record count. So, if I have 24 lines for the bills #23433, I will have 20 "good" lines in group 1 and 4 "good" lines and 16 "blank" lines in group 2.
4- In my report, I regrouped the fields by bill number and then by group. So, I have only 20 lines per page and I can have the sum, taxes, ... for each page.
That's it...
But if someone can come up with a better way to do it or see a big flaw in my logistic, feel free to reply.