The BMA has confirmed that efforts to appoint an investigator are ongoing and that it remains 'on track' to have someone in post before the end of May to lead the two-month process.
A top official has also written to senior GPs who spoke out about sexism - offering assurances over the the investigation and further detail on how it will work.
After the BMA published details of the terms of reference and scope of the investigation last month, Dr Stephanie DeGiorgio, Dr Amy Small, Dr Katie Bramall-Stainer and Dr Zoe Norris highlighted concerns over the plans.
The four GPs - all current or former members of the BMA's GP committee - warned that the investigation must not be limited to sexism and sexual harassment and that it must also consider other unacceptable behaviour.
In a letter to the four GPs, BMA consultants committee deputy chair Dr Helen Fidler - one of two BMA officials responsible for setting up the investigation - confirmed that it 'will encompass all instances of discriminatory or poor behaviour which might be considered to be related to sexism or gender bias'.
'Internal digital communications' within the BMA will be included in the investigation and it will be 'open to input from both current and past BMA members', she confirmed.
The letter says: 'It will explore all the organisational, systemic and cultural factors in the BMA that fail to promote gender equality, including how this may have impacted on members’ appointments to non-elected positions within the association.
'We are making arrangements to ensure that all disclosures made to the investigator are treated sensitively and confidentially, and that individuals are able to participate in this investigation without fear of detriment. If anyone wishes to make a formal complaint, we will offer access to an independent complaint handler to remove any perceived barriers to doing so through current channels.'
Dr Fidler confirms that the 'full investigation report itself cannot be shared with the wider BMA membership due to the need to protect confidentiality of those who provide evidence', but says that its key findings and recommendations will be shared in full.
In a joint statement, Dr Small, Dr Norris, Dr Bramall-Stainer and Dr DeGiorgio said: 'We collectively contacted the BMA after their initial outline for the investigation was shared, with some concerns as to its scope and terms of reference. We are pleased the BMA has taken these concerns on board and been willing to reassure and clarify their intentions on a number of points.
'All we have wanted to achieve is a safe process for those affected by inappropriate and unacceptable behaviour to raise concerns with the BMA. There are broad issues to be addressed, and some significant reflection required within parts of the organisation.
'However, the commitment thus far has reassured us that the inquiry is something we are happy to engage with fully. We would encourage all colleagues who have been affected in the past or continue to be now to do the same and end this behaviour permanently.'
The letter from Dr Fidler adds: 'Sexist, disrespectful, discriminatory and abusive behaviour simply has no place in the BMA and must be stamped out, and it is only through learning from and responding to the negative experiences which some members have unfortunately had that we will be able to accomplish this critical goal. Thank you again for raising this issue.'
The BMA apologised and promised an urgent investigation at the start of April after GPonline published an article by Dr Norris and Dr Bramall-Stainer warning that sexism had cost general practice a generation of leaders, and reported on GPs' concerns over a 'sexist culture' in the BMA.