They do spread themselves around, but the leaves due down in early summer and if you don’t want the attractive and colourful (but toxic) berries the stems bearing them are easily removed. They are however a good food resource for birds and small native mammals.
Just supervise small children around them.
“I am not lost, for I know where I am. But however, where I am may be lost.” Winnie the Pooh
Posts
aka Arum maculatum
https://www.rhs.org.uk/Plants/1660/Arum-maculatum/Details