Sexually mature GP with 2 adults

[Neonmiriad]

Good evening, me and my partner bonded our 2 adult guinea pigs with a new baby, 8 weeks old when we got her, about 3 weeks ago. The bonding went well and it's been fine up until today.
Swsi (welsh spelling) is around 3 months so is coming into sexual maturity. Today both our other guinea pigs, one male and one female, have been very interested in Swsis rear end, and have both been mounting her all afternoon, around 2 hours and it is continuing as I write this.
Derek, the male, is neutered, and Thelma used to to have a sister who passed away late last year, so there used to be 3 of them together.
Is this bonding behaviour we are seeing, is it part of the sexually maturity of Swsi or could it be that they have started to not get on?
No blood has been drawn but we are concerned because of the heat and it is relentless.
Swsis reaction can be to lie down and accept the mounting, but the longer it has gone on, she is running away more and squeeking, but is still accepting the mount.
Any help would be very much appreciated.

 

[Piggies&buns]

This all sounds very normal as she is probably coming into season.

 

[Wiebke]

Good evening, me and my partner bonded our 2 adult guinea pigs with a new baby, 8 weeks old when we got her, about 3 weeks ago. The bonding went well and it's been fine up until today.
Swsi (welsh spelling) is around 3 months so is coming into sexual maturity. Today both our other guinea pigs, one male and one female, have been very interested in Swsis rear end, and have both been mounting her all afternoon, around 2 hours and it is continuing as I write this.
Derek, the male, is neutered, and Thelma used to to have a sister who passed away late last year, so there used to be 3 of them together.
Is this bonding behaviour we are seeing, is it part of the sexually maturity of Swsi or could it be that they have started to not get on?
No blood has been drawn but we are concerned because of the heat and it is relentless.
Swsis reaction can be to lie down and accept the mounting, but the longer it has gone on, she is running away more and squeeking, but is still accepting the mount.
Any help would be very much appreciated.

Hi and welcome
It sounds normal for a sow coming into a stronger season. your younger girl is slowly coming up to teenage when stronger seasons become more common, although the individual variance can be quite massive.

You may find these two information guides very helpful on what to expect:
Sows: Behaviour and female health problems (including ovarian cysts) (includes a chapter on seasons)
When Sows Experience A Strong Season (videos)

PS: Please be aware that sows have their first season between 4-6 weeks and that boars start making babies between 3-5 weeks - that is basically from weaning age onward until the day they die for both genders. We see a lot of these early pregnancies due to mis-sexing or the sale of already pregnant sows.