The guidance has been recently "clarified" (this is the wording the HO used) and it is indeed harsher with people who entered illegally. Your mother and sister have the issue that they not only entered illegally but also made what is classified as a dangerous journey. Were you ever granted refugee status?
The gudelines state
https://assets.publishing.service.gov.u ... racter.pdf
Illegal entry
Any person applying for citizenship from 10 February 2025, who previously entered
the UK illegally will normally be refused, regardless of the time that has passed since
the illegal entry took place.
Any person applying for citizenship before 10 February 2025 where illegal entry is a
factor, will continue to have their application reviewed to determine whether that
immigration breach should be disregarded for the purpose of the character
assessment.
As your family made a dangerous journey this amendment to the guidance seems to exclude your sister and mother from being eligible for citizenship.
However the guidance also states
Defence for a refugee charged with certain offences
When considering an immigration related conviction received by a person granted
refugee status, you must consider whether the person has a defence under section
31 of the Immigration and Asylum Act 1999.
Section 31(1) provides a defence for a refugee if they have committed or attempted
to commit an offence under section 31(3) or (4), if they have come to the UK directly
from a country where their life or freedom was threatened (within the meaning of the
Refugee Convention) or they could not reasonably have expected to be given
protection under the Refugee Convention in a county they were in immediately
before arrival in the UK, and if they:
• presented themselves to the authorities in the UK without delay
• showed good cause for their illegal entry or presence
• made a claim for asylum as soon as was reasonably practicable after their
arrival in the UK
So it may make a difference if you had refugee status. I would advise speaking to an expert solicitor about this as the change is very recent still.
All advice comes from personal research and experience and should not be regarded as professional opinion.