Yes it's true. But if I were Engels I would never financed that kind of idea I disagreed with. On the other hand we always was taught at the school as "Marx and Engels" not just Marx. This was the "canon". And the authors of "Communist Manifesto" were Marx and Engels not just Marx.

Btw: nowadays Marx is a topic again, especially in the scientific area, regarding his "Das Capital". Imho it is similar to the world economical collapse in 2008, when John Maynard Keynes' theory was brought up again in contrast to Milton Friedman's neoliberal theory.