Need lisp to edit Mtext
By "a specific line" do you mean some specific text string as part of its contents? Or [for example] the third line down from the top, whatever that contains? If the latter, would it be the third line as the result of internal hard returns [a routine could find those] or just of word-wrapping [I'm not sure a routine could determine that, and it would vary if the defining-box width is changed]? An image or small sample drawing with before and after would help.
Kent Cooper, AIA 
Here's how AutoCAD stores the text content of your "after" Mtext object, which is in the (1 . "Text content") entry in entity data, or the TextString VLA property:
"TITLE\\P \\PGENERAL\\P \\P\\pxi-3,l3,t3;A.\tLINE1\n\\PB.\tLINE 2 \n\\PC.\tLINE 3\\P\\pi0,l0,tz;\\PSPECIFIC\\P\\P\\pi-3,l3,t3;1.\tLINE 1\\P2.\tLINE 2\\P3.\tLINE 3\\P4.\tLINE 4"
The \\P's are hard returns, and the \n's are new-line characters [why they're not also \\P's, I couldn't say, but it's probably related to being within bulleted content]. The \t's are Tabs. The \\pxi-3,l3,t3; must be about the beginning of letter-designated bullets, the \\pi0,l0,tz; about the end of those, and the \\pi-3,l3,t3; about the beginning of number-designated bullets [note the absence of the x that's in the letter-based one]. I don't know exactly what the components of those bullet-related codes mean. The A. B. C. and 1. 2. 3. 4. bullets themselves look like just plain text characters, but they're clearly under the influence of those bullet-triggering codes, because if you edit out a bulleted line, the subsequent lines get different bullet letters/ numbers.
It may be possible to get a routine to inject those kinds of codes into the string content of Mtext that doesn't have them. But having a routine find where to put them would be a real challenge. There would need to be some type of constants to look for. I assume there would not always be three and only three letter-designated ones, so it couldn't just count through a certain number of hard returns. And I assume the "TITLE" would not be that word. Would the headings "GENERAL" and "SPECIFIC" always be there, always exactly like that? Would there always be blank lines between the letter-designated ones but not between the number-designated ones?
Kent Cooper, AIA
