Why am I being asked to completely merge 4 rooms?

In fallout shelter, on android, one of the objectives that may come up is to completely merge four rooms. However, as stated in this question, you can only merge a maximum of three rooms together.
Is this a bug, a typo, or am I missing something entirely?
Best Answer
Build a Power Plant three rooms wide. Upgrade it all the way. Build a Water Plant three rooms wide. Upgrade it all the way. Build a Diner three rooms wide. Upgrade it all the way. Build a Hospital / Science Lab / Storage Room / Radio Room. Or ANY three rooms that can be merged together. Do that four times. Boom. Objective finished. [Merge Three Rooms; Four Times]
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Is it better to merge rooms in fallout shelter?
Most rooms can also be merged up to three times by placing an identical room of the same tier next to it. Generally, each room can facilitate two dwellers. Merged rooms may be occupied by up to 6 dwellers....Room time.Time PoolRoomPool SizeBase Time (in minutes)Water Purifier120020Bottler120020MedBay2400407 more rowsCan you merge 4 rooms in fallout shelter?
In fallout shelter, on android, one of the objectives that may come up is to completely merge four rooms. However, as stated in this question, you can only merge a maximum of three rooms together.How do you merge 3 fully upgraded rooms in fallout shelter?
Fallout ShelterIf two rooms aren't on the same upgrade level, they won't merge. In that case you will have to upgrade the other rooms as well so they can merge. It happened with my 2 power rooms. They merged after I upgraded them both.Fallout shelter ep.3 (fully merged rooms)
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