You bring migrants from dysfunctional societies (that they have created) , pay them, house them, , feed them make sure they can sue you right to the supreme court, at your cost, Give them time so that they can chase your daughters while you are at work paying taxes, saving,---
of course you are going to develop a new class of people that prosper in that lifestyle, produce more children then you, exponentially. so, before the overlapping generation expires, Europe, as we knew it, will be gone.
Create a niche, and life will find the perfect match. Is it evolution Biological or Social? not a nice niche.