@MichaelMulvaney I am nearly certain this is Silene vulgaris (as is dad, who was aware of this species in his alert lists), but would just like to double check as I think it would be a new occurrence for the ACT.
Yes, I don't think Silene appears to be super invasive - we had a pretty large patch of Silene gallica along our road but after just pulling it out over 2 sessions it appears to be gone already