First state the limiting condition. 방문하기어려운경우에는요? asks about an alternative when the preceding advice requires a visit. The topic must be clear from the conversation.
Pattern
Example
When a visit is not possible
방문하기어려운경우에는요?
Time constraint
오후다섯시전에갈수없는경우에는요?
A condition and an alternative
방문하기어려우면전자우편으로받을수있어요?
An unconfirmed option
대리수령이가능한지확인해봐야해요.
Compare 어렵다→어려우면 and 바쁘다→바쁘면. 경우에는요? is a short follow-up based on the previous context; 어려우면 …? can name an alternative.