Above ground pool drain installation

[Fredartic]

I just reinstall my 21 ft Aqua Leader pool with a new drain. While I finish preparing and smoothing the ground with sand before putting the liner, I notice that the drain mooves a little when I'm walking on... Is it normal? Do I need to stabilize it to avoid problems in the future? Or with the weight of water, it won't moove anymore? Thank you for your advices.