Well MT as I am an old hand at both actual drilling of water wells and caseing and setting pumps I will attempt to address your well issue. First requirement is water and finding that isn't .necessarily easy, but the driller obviously did and it was in his opinion that this was viably useful for the owners purpose (much water is too " salty" with high mineral content of some type) and if the water was bad there ends the project in that specific location. If good flow he would have also checked the wells flow rate in gallons per minute. If flow of these two determinates were satifactory the driller would install steel bore caseing, in my day most was steel) to prevent the hole bore from collapsing with time. Western Oklahoma was covered with wind motor pumps and towers, but by the 1950's their use was almost over as electric pumps took over.
The final step of installation comes with setting the pump two types to select from. Down hole submersible or a lifting pump, at times both were used on deep wells some of which were hundreds of feet deep. Many were really shallow twenty or 30 feet wasn't uncommon either.shallow or deep hole the water flow could be high or very modest. Some deep wells were completed in valleys, while good shallow wells at times were encountered on hill tops. Typically a local "water witcher" was employed by the land owner to mark the location where the driller would dig. I used a high powered rotary rig, truck mounted with which to both dig and set caseing with it's "sand line" tower winch. It used 20 foot long drillings rods to bore.
Once the pumps were set the pumps primed and all air bled from the water lines the well was ready for use.
Long story but it helps to know how it works before chasing answers. I actually can only guess and being a driller I have several but most relate to having air in the water lines. Having added to an existing line which I assume at one point worked well, would greatly add to this as being probable. Not knowing what degree of expertise was actually used in putting the additional well in service and coupled to a second well and pump and then distributed to different households existing plumbing (all of which should have been simultaneously bled of air) and if not done in concert the system will shake and groan. This process may take more than one attempt.
If both time and money can be expended a competant plummer can coordinate the proceedure as all families have to cooperate to get this done. Believe it or not this is the simplest solution, but if the problem is at the well and is an actual well or pump problem then the above cited process still has to be done.
No solution but the process involved in tackling the problem. A well technician may be necessary to double check both wells for water flow in the well, not output. One well may be low volumn water flow and or one pump pulling to hard and drying one of these wells and pulling in some air, it doesn't take much) instead of water. I would not have piggybacked two wells and pumps to the same existing distribution lines, but that's the cheap way to do it. If one new pump was added to an old pump from the other well and they were rated at different flow rates, air could be pulled in. So many variables possible if this is a home built system, most of them errors.
Long post that barely scratches the surface so PM me if you can stand more, but This is how I would approach it
Rick C.