Hello, @alfred-streich, @alan-kilborn and All,
As, seemingly, all lines, which must be joined to their previous line, do not contain any colon symbol ( : ), an alternate syntax, to the Alan’s one, could be :
SEARCH (?-i)</para>\h*\R+\h*<para>(?![^\r\n]+:)
REPLACE \x20
Notes :
First, the in-line modifier (?-i) forces a non-insensitive search process
The part \h*\R+\h* matches any range of horizontal blank char(s) ( Space and Tab ), even null, followed with a non null range of line-breaks ( \r\n, \n or \r ), itself followed with an other possible range of blank char(s)
The part (?![^\r\n]+:) is a negative look-ahead structure, which defines a necessary condition for the overall regex to match, although not part of the final match, and looks for a line with does not contain any colon character, after the literal string <para> till its line-break
Note that the [^\r\n]+ defines a non-null of characters, different of EOL chars. So, any char after <para> till the colon symbol : !
In replacement, the syntax \x20 is the hexadecimal representation of a space character and you may, as well, write a single space char in the Replace with: zone
Best regards,
guy038