When the following word's (noun, or adj.) first letter is a vowel or κ, π, τ, μπ, ντ, γκ, ξ, or ψ, the final -ν is not ommited. When the following word's (noun, or adj.) first letter is β, δ, γ, φ, θ, χ, μ, ν, λ, ρ, σ, ζ, the final -ν is ommited.

This rule only applies to the feminine gender. ^.^

Διαδοχή may be a translation to order, however it's not that commonly used, especially in such cases. Διαδοχή is mostly used in the meaning of succession (for example, succession of a throne.). However, the verb and the adjective, διαδέχομαι and διαδοχικός, are something one might come across more often in texts or speech. ^.^

(Also, keep in mind that hints are a form of 'dictionary'. We have to include all possible meanings, even if they aren't interchangeable in all cases. So don't be taken aback if you choose a word from the hints and it is nowhere to be found in translations. :P)