Ask rather than assume
Start with what your relatives want to do. Age alone doesn't tell you someone's preferred pace or mobility. Discuss walking distance, stairs, shade and how long they want to be away from home.
Keep personal medical questions private and let the person decide what the organiser needs to know.
Verify the route through the venue
Ask about the distance from drop-off to the activity, the surface underfoot, toilets and places to sit. “Easy access” is too vague when a specific step or steep path could decide whether the visit works.
Choose a shared route that fits the whole group. A longer extension can be optional for others if there is a comfortable meeting place.
Keep departure flexible
Set an expected finish but allow an earlier return. Make sure the transport arrangement supports that choice rather than requiring everyone to stay until the last activity.
Before choosing Aburi Botanical Gardens or another outdoor venue, confirm the actual facilities for your route. Put rest and meal stops into the plan first, then decide whether another attraction still fits.
Rules, fees and opening hours change. Confirm anything that matters before you rely on it.