The Chaplains Returns of baptisms, marriages and burials 1761-1880. From 1880 they were known as “Army” Births, Deaths and Marriages and from 1959 “Forces” Births, Deaths and Marriages. These records include the registrations of British armed forces (including serving members who were not British nationals) posted overseas.
In 1914 the Royal Commission on Public Records said ‘There is reason to believe that this class of military record has neither been preserved nor transmitted with sufficient care’, so there are many BMD events which are not available.
In particular, the Army Chaplains Returns of Burials most likely do not include many deaths in action, or associated deaths in camp or on the march, including deaths from disease, such as cholera or heat stroke, where a chaplain did not conduct the burial service. The documentation does not appear to cover this point. The Muster roll records should include these deaths.
The Chaplain Returns records were compiled by regimental chaplains and may also be duplicated within the regimental records. The Overseas Section of the General Register Office in Southport holds these volumes and the indexes can be viewed at The National Archives (TNA) and online. The Overseas Section of the General Register Office also holds additional records of regimental marriages taking place between 1761 and 1924 that have never been indexed. As these additional records have never been indexed, they are not included in the data on findmypast or other websites. If you can provide the man's name and regiment, and approximate date the GRO will search their records. Email the GRO with GQ in the subject header, eg "GQ Regimental Marriage Registers", to avoid receiving an automated reply. A list of the regiments covered in the unindexed records used to be available, but it is not known if it currently is. 
As an example of a record from the Army Birth Returns, a researcher has advised he has a “certified copy” from the GRO taken from “Army Book 112 (Register of Births) of the -th Bn. -th Punjab Regiment for the six months ending 30th June 19-- reported from the Military Station at Isak (North Waziristan)”. Note this Regiment was part of the Indian Army.
He advised: I suspect the official recording and reporting of such events as births to British or foreign Indian Army soldiers’ wives were likely to have been done almost entirely through their Army channels with not a Chaplain in sight and would be dependent on the British/foreign father reporting the birth, although one needs to allow for delays in reporting - I was born before the six months specified above In my case it looks as if my father reported my birth to his adjutant a couple of months or more after the event when he was on operations (that means in a war situation) in Waziristan. 
The indexes in respect of the overseas registrations are most commonly called the British Army Overseas Indexes.
The LDS have microfilmed some of the indexes, as listed in this Library Catalogue entry and you can order the microfiches and view them at Family History Centres. However, the indexes are available online, see below.
Note that if a record is available both in the India Office Church records (now available on findmypast) and in the General Register Office records, the latter may contain more information, at least for some time periods. By way of example, in 1903 the additional information available for a marriage record was the nationalities of the groom and bride, and the occupations of the fathers of the groom and bride.
- British Army Records. In particular, the WO97 records described in Section 4.1.2 Service and pension records, available on findmypast, may include information about marriages, births of children or deaths of family members. It may be helpful to view the WO97 record first, before pursing the records mentioned above. Some muster rolls also include married rolls for the regiment.
- Familyrelatives.com contains the Overseas Indexes, which include images from the British Army Overseas Indexes which you can access for free, (even though most other records on the site require a subscription) However first you must log in. This site requires a Adobe Flash 11 plug-in. Log in from the Home Page. Then select 'Search' and then 'Overseas Records'. Then select the database you are interested in. Note, some pages from the indexes appear to be missing, so the database is not complete. Missing marriage pages have been noted.
- findmypast has the British Army Overseas Indexes (for which there is a charge to search). However, in addition, the database contains indexes for births in the U.K. and overseas, 1761-1924, taken from regimental registers, including births in India. Search in the category Birth records. The records themselves are held by the General Register Office, and are not on open access. In respect of "Regimental Birth Indexes –[these] may show several index references for the same person. As a soldier moved from one regiment to another, he had to register himself and his family each time for pay purposes. If you find more than one index reference for same person, provide all references and we will produce the entry with the most information". As noted above, WO97 records are also available.
- If you have found an index reference and you then want to order a certificate, this can be done online from the GRO. (A charge applies). This will be a transcript, not a copy of the original document.
- National Archives Guide Looking for records of a birth, marriage or death in the armed forces
- British Births, Marriages and Deaths Overseas Family Search Wiki
- "At the FRC [now closed] is a list of the marriage registers, arranged by regiment; if your regiment is there, with entries for the right period, ask at the enquiry desk in the FRC to be put in touch with the Overseas Section, which may conduct a search for you." Thread from British-Genealogy.com, quoting Tracing your Ancestors in The Public Record Office by Amanda Bevan (Public Record Office Handbook No.19, sixth edition) page 187-188: Section 181.1.1 For details of this book see Waiting for review
- By email to User:Maureene, 23-24 Feb 2010
- Certificate ordering Service: Most customers want to know... www.gro.gov.uk (Scroll down)