Manager being unsafe and she's a bully, too

[citychick]

I'm a swimming teacher. The manager from another pool was covering for annual leave.
We have 2 pools, one for very young children and a large one for older swimmers.
I hadn't finished my lesson with very young children when she barged in and put her tweenage swimmers in my pool. I was surprised as this doesn't happen. I observed and then asked her what she was doing. "Oh, I put the kids in here to warm up after lessons."
This is not general practice, and it meant that there were too many kids in a small pool. I said firmly, "Please, not in my lesson, don't do this again.
She was livid.
She has complained to our site manager, who she knows will back her. Despite it all being on cc tv.

She was unsafe, she didn't ask my permission and she has made a complaint.
Any advice, please. I know I have outed her bad behaviour, and she's trying to take me down.

Thanks for reading.

Fire back just as hard and don't back down. What she did was goes against policy and was unsafe. File a complaint against her.

is there a policy that specifically states this to back you up?

Thanks, good point about policy. I'll check with Swim England and the site policy. Another teacher had previously been asked not to do this and stopped.
Yes, I plan on standing my ground. I'm an experienced teacher. These issues don't often happen but seem to when she's around. Thank you.

Crawl through the NOP of your pool for anything and everything that will back you up.
Just to clarify, (because Im having trouble believing they did it, but hey ho, managers…)the manager put pre-teen swimmers in a training pool to ‘warm up after lessons’.
How many pre-teen swimmers joined you?
Did the manager stay and take some responsibility for the swimmers they left in your pool, regardless of their swimming capabilities?
How many younger children were you in charge of at the time, prior to the other swimmers entering the water?
Your lesson plan was formulated to include the younger children in the training pool.
you had neither planned for nor risk assessed the arrival of other swimmers.
Although your training means you can teach swimmers of varying abilities in this particular instance your own lesson was interrupted by other older swimmers, which may have upset the play orientated atmosphere of early years lessons, thus beggaring up your lesson.
If the manager walked off they effectively left you in charge off your own lesson and the other children. That was how many children??
They were at the very least rude, definitely unsafe. They put your pupils at risk, the children they put in the pool at risk if they left and you were overstretched. Even if nothing happened, so what, stick to your guns and fight it so they don’t do it again.
’Warm up after the lesson’ 😳 Swim harder, Swim harder!!

To clarify...the big pool is a colder pool and small pool is warm for young children and babies so it was literally warming up towards the end of the lesson, however it's unnecessary.

6 to 8 preteens entered the pool, adding to my 8 small children. Also another 6/8 children on other side of the pool as its roped in half for another lesson.
No plans made for this addition. This is not a planned procedure. She simply waived it off. Yes, I was interrupted.
The duty manager was on poolside at the time, and I asked him about this. He knew nothing.

Yes, it was rude. Yes, it was potentially unsafe.
I made it clear I wasn't OK with it , there were parents watching . They may have complained.

It's all on cctv.
Thanks for your imput.