Child support: each month we exchange child support amounts based on income. Does CRA want each of these or just the Net amount received or payed?

for example: I pay her $1000, and she pays me $1500. In my tax form do I fill in lines (12799/12800: 18000 received) and (21999/22000: $12000 made) or just the net amount which in my example it would  written to 12799 as $6000.