Welcome,
@Ashleycunliffe. You have attached your picture and question to my picture in the 'Miss Kim' lilac database and I am not sure if anyone else will see it. You might have better luck posting your picture and question on the Perennials forum.
https://garden.org/forums/view...
I am afraid that I do not have any advice on keeping it from falling forward other than to put a stake in the ground and tie it up. My lilac in the picture has to get cut back in order to keep it from getting in the walkway. One year, I cut it back by at least a third. I was hoping that I hadn't killed it, but it has come back beautifully.
