TheRhubarb - it wasn't that I misbelieved you, I was just confused by your post. It isn't so much that the Catholic Adoption Society have to adhere to the LA's assessment criteria. As far as I'm aware all LAs, and voluntary organisations (like the one you mention) follow the same guidelines for the recruitment, training and assessment of prospective adoptors. This means that they put on training/preparation courses for prospective adoptors so that they may learn far more about the adoption process, and the reasons why children need to be adopted and about some of the behaviours that they wil have as a result of being abused/neglected in the past.
As far as I am aware all LAs, vol orgs (like the one you mention) follow the same procedure for assessing applicants. This is produced by the British Agencies for Fostering & Adoption (BAAF) and is usually known as the Form F. Now I am 8 years out of LA practice (am retired) and I do know that BAAF change their forms and the format, sometimes to make it easier to carry out the assessment. However I can assure you that these assessments are very comprehensive, covering all aspects of the applicant's lives, the way they were parented and their own parenting capacity to name but a few. Alongside the assessment there will be comprehensive checks, CRB checks, medical checks (this takes the form of a questionnaire being provided to the applicants and they then have a medical with their GP. The GP will then send the medical report to The Medical Advisor for the LA (assume that vol orgs have their own medical advisor) and the medical advisor, on the basis of the GP report makes a decision whether the applicants are suitable adoptors on the basis of their medical history. Additionally the applicants will be expected to provide referees (rules on these do change between different LAs and Vol Orgd) but it is usual to ask for 2 family referees, and 2 independent referees.
The applicants are often invited to write something themselves about their lives, though this is not essential.
OK let's take the Catholic Adoption Society who undertake an assessment; they cannot place children for adoption a) because they don't have any children and b) because it is illegal and has been for many years, though I can't tell you exactly when.
So if Mr and Mrs x have been approved by the Catholice Adoption Society and it is legal for them to have their own adoption panel to recommend them as adoptors. Now what I don't know is whether people approved by this society will only want to place children whose birth parents want them to be brought up in the Catholic faith. However the next thing for the CAS to do is to find out from LAs (who are the only authorities who actually have children in their care that are awaiting adoption) whether they would like to "buy" one of the approved families. It may be that the CAS have applicant(s) who are considering a child with disabilities or a large sibling group (as these are very hard to place children) and so the LA may be interested in such applicants. The Vol oRgs send round to LAs details of their families who are approved adoptors to see if there is a "match" - however because of the cuts in budgets LAs are seldom able to "buy" the family because they cannot afford to do so. However if the LA are interested in "buying" adoptors from the CAS (or any other vol org) they will scrutinise the assessment in the same way as they would their own assessments. There would be no question of the CAS assessment being very scant (as used to be the case many years ago).
I'm sorry I can't comment on your sister's case.
As far as your mother and step father are concerned, they must be registered with a LA or an IFA (Independent Fostering Agency) to be able to foster. If they have been approved by an IFA, the same thing will apply, they would have had to have been comprehensively assessed, and the IFA would then have to "sell" them to the LA, or to put it another way the LA would have to "buy" the placement from the IFA. So your mother and stepfather must be registered foster carers, as they are still taking places. By law all fost carers have to be reviewed on an annual basis to ensure that everything is going well, and the age range of the childen they foster is still right for them.
I appreciate that you are very concerned but I can only tell you what the process is, and has been for many years. I will look up when it became law that only LAs could be adoption agencies that could place children and let you know.