Get user and users of ancestors of a model instance if it has `organizationmember` attribute or else only user of the instance in Django

Question

I have the following models:

class Client(BaseModel):
    #other fields
    engineers = models.ManyToManyField(Engineer, null = True, blank = True, related_name='clients')

class OrganizationMember(MPTTModel):
    designation = models.CharField(max_length = 100, blank = True)
    user = models.OneToOneField(User, on_delete=models.CASCADE)
    
    parent = TreeForeignKey('self', null=True, blank=True, related_name='children', on_delete=models.SET_NULL)

Now I would like to get all engineers of a client instance and check if each engineer has an organizationmember instance or not. Then if they belong to some organization then I should get_ancestors of that organizationmember and then the users. If they do not have any organizationmember then just get the user of that engineer instance.

For this I have written a method in Client model as below:

class Client(BaseModel):

    def get_users_from_engineers(self):
        users_in_organization = []
        users_outside_organization = []

        engineers = self.engineers.all()
        if engineers:
            for engineer in engineers:
                user = engineer.user
                if hasattr(user, "organizationmember"):
                    users_in_organization += [orgmember.user for orgmember in user.organizationmember.get_ancestors(include_self=True)]
                else:
                    users_outside_organization.append(user)

Now this code is working correctly but I am sure that I can use django filters here instead of two for loops and optimize this code. But I do not know how.

For eg:

OrganizationMember.objects.filter(user__engineer__in=self.engineers.all())

can be used to get all the organizationmembers of the engineers of that particular client instance. But I need the users of those organizationmembers. Also if I use get_ancestors on multiple engineers then more than one engineer might have the same ancestor thereby adding the same person more than once in the users_in_organization list. How can I rectify this if I use django filters?

Edit:

In the method get_users_from_engineers I can also use as follows:

users_outside_organization = list(User.objects.filter(engineer__in=engineers, organizationmember__isnull=True)

But I do not know how to get the users_in_organization values as stated above using django orm methods.

Note: This is my first question in codereview. I do not know if this question should be asked here or in stackoverflow since I already have a working code. Anyway I have asked the same question in stackoverflow also. Please feel free to correct me regarding the same.