More on '!?'/'?!'

In The Meaning of !? and ?!, I asked, 'Assuming that Fischer's use of notation is consistent, in what circumstances did he apply '!?' and '?!' to other moves in My 60 Memorable Games?'

I flipped through the book looking for instances of the two symbols. I found plenty of examples for '!?', but none for '?!'. Fischer used '!?' to mean speculative, sharp, or risky. In the Keres game under discussion he attached the comment 'a risky selection in time-pressure'. I found one other example where '?!' might have been more appropriate than '!?' : Fischer - Bednarsky, Havana 1966 (game no.55) 9...Nfxe4!?, where Fischer wrote, 'Playing with fire.' This is consistent with 'risky'.

Interested in the history of the symbols, I first checked Winter's Chesshistory.com. There I found Chess Notes Archive [21] (April 2006), '4330. Punctuation: Can readers improve on past efforts to find the earliest instances of moves being awarded exclamation and question marks?', and '4335. Punctuation: There are plenty of examples of exclamation marks in the BCM of 1881 before page 124.'; plus Chess Notes Archive [22] (May 2006), '4342. Punctuation (C.N.s 4330 & 4335): Exclamation marks became prevalent in the Deutsche Schachzeitung in 1861, but at first the custom was to attach them to moves by Black in compositions, in the sense of ‘the best defensive try’.' I found nothing about the hybrid symbols '!?'/'?!'.

While I'm on the subject, Winter's generic term 'punctuation' is not used universally, although it is concise and descriptive. Hooper & Whyld used the phrase 'conventional symbols'.

When did the symbols '!?'/'?!' come into standard use? The earliest Informant I have at hand is no.15 (1973H1), where they are used. Some other resources at hand: Alekhine's Best Games (1927 & 1939): no; Keres' Complete Games (1964): no; Larsen's 50 Udvalgte Partier (1969): yes, also '(!)' and '(?)'are used frequently; Wade & O'Connell's Fischer's Chess Games (1972): yes; Botvinnik's Best Games (1972): no, but Karpov's Road to the World Championship (1978): both used at least once, perhaps no more; Tal's Life and Games (1976): yes.

The symbols '!?'/'?!' appear to have come into use in the 1960s and were widely adopted in the 1970s. Their adoption was undoubtedly due to the widespread popularity of Informant's publications. Why did Informant decide to use them?

NB: All of these book searches were done quickly. It's possible I overlooked something. • Wikipedia's page on Punctuation (chess) has several alternate definitions, but no history.