NC as details may be outing.
Partner A lost their mum back in 2016 and she was cremated. Her wish was to be scattered abroad, and so the discussion of scattering ashes wasn't discussed straight away due to finances. It was some time later (maybe 3 years) that partner B mentioned that they should maybe discuss what to do and when RE the ashes, but it was clear that partner A wasn't ready to take that step. It was at this point that the idea of counselling was broached, and partner A did do this for some time, to the point that they felt ready to make plans with the ashes, although they weren't in a rush which was fine. Counselling did highlight that a lot of partner A's traits could be related to their upbringing, specifically that they are such a people pleaser.
For context, partner A didn't have a good upbringing. They were brought up an only child, mother alcoholic, father abandoned them for several years then popped up again as a teenager, was moved around a lot including a move of country, was working from age 13 to help support their mum as money was very tight etc.
One big further detail. When partner A was 5yo, their mum had another child which was put up for adoption. This sibling has gotten in contact with partner A in the past few months and they have been slowly building up a relationship. Sibling lives in another country so no meeting in person has taken place. Partner B very supportive of the relationship. Sibling has expressed a wish to travel to the scattering of ashes and meet partner A for the first time. Everyone on board with this, and plans are loosely made for 2025.
Now onto the dilemma. Partner A's mum had two good friends. They never lived close to partner A in their lifetime so weren't involved in their childhood (or adulthood). They would definitely be described as the mum's friends, not family friends if that makes sense. Both lovely ladies, but not close enough to invite them to our wedding for example - other than the funeral probably haven't seen either of them for 15 years. Partner A let them know that sibling has gotten in touch - they knew about the adoption at the time and partner A wanted to let the friends know that sibling has done well etc. Scattering of ashes was discussed as obviously partner A was asked if they and sibling planned to meet. The friends have now asked if they can tag along on the trip.
Partner A doesn't see the harm and thinks it's nice they want to join. One of the friends didn't make it to the funeral so thinks it would be good for her for closure.
Partner B thinks that scattering of ashes is a family thing (funerals are open / public for anyone who wants to come along, but scattering of ashes are private). In this instance it is also the first meeting of partner A and sibling so it's going to be a highly emotional trip, and so as much as they have no bad feeling towards the friends partner B thinks in this case they have been highly inappropriate and partner A should say no. Partner B did not have a good relationship with partner A's mum when she was living, so also worried that the friends have a pre-conception that partner B is a bad person and feels they would be uncomfortable spending several days with them.
Sibling has been asked for thoughts but hasn't come back yet.
YABU - the friends aren't unreasonable to ask, and partner A should say yes (if sibling also agee's)
YANBU - the friends are being very inappropriate. Partner B should say no to them coming on the trip