The number of women who experience late pregnancy, birth and recovery without any complications is very low. (I got unlucky on all three 
)
I would have hated visitors staying in late pregnancy. I outgrew my maternity clothes so spent the last weeks sitting on the dining chairs or in bed in my underwear at 15oC. I only got dressed in my few remaining clothes on the rare occasions I was taken out of the house and had no way to get out indepdently. I was sleeping appallingly due to SPD pain. It was short bursts of varied company that was needed, not long-stay guests. By the last week, I had to stand sideways on to reach the sink. I was not physically capable of hosting/ most household jobs and could barely stand up unassisted.
I had 24 hours of labour at home. I had some very, very close friends come round while the contractions were still building up, but they went when hours of regular pain were begining to take their toll. There were several trips to the assessment ward to check progress before being kept in.
Neither my EMCS nor VBAC had pretty outcomes. First time by the time we came home after 4 days in hospital including 36 hrs in HDU, I was physically and mentally broken. I remember the feeding cycles of trying to get some milk, any milk into DS who was reluctant to start feeding. Biological functions were not pleasant, it was not just weeing in the shower as I was on strong doses of laxitive. Second time, I was sitting on frozen sweetcorn for weeks. I didn't leave the house for a month for anything non-essentually medical.
MiL came to stay for two weeks after DH's paternity leave finished to look after the house and support me with baby. She was brilliant, but those extra 2-3 weeks of adjustment made a massive difference. She was one person with her own space in the guest room. She also went to BiL for the weekend in the middle to break the stat up. I had some clothes that fitted by then! First time, I only had a couple of mat/ feeding trousers as my under-the-bump leggings rubbed on my wound and I had to buy over the bump trousers to last me a couple of months until I could just wear up-sized normal trousers.
So, NO, NO, NO. One trusted, helpful person can be fine. Four people, particularly including teenagers and no private space is an absolutely hellish plan. The timing is terrible as it straddles the phase when you are most likely to give birth.
Get them to cancel. Get them to rearrange for months later. Get them to book accommodation in the next county, but in no way tolerate them staying or even hanging around for lengthy periods. I hope all goes well, but even under the best circumstances, birth is a very vulnerable time.