both can be attributes
but you can use atvlnk.lsp function to link the value of one attribute (source) to the other (target) as a field
then when the source changes the target will change with a regen:
; atvlnk selects Texts value or Attribute inside Block and link to another as a field
(defun c:atvlnk (/ Get-ObjectIDx64 en en1 txt)
(vl-load-com)
(defun Get-ObjectIDx64 (obj / util)
(setq util (vla-get-Utility (vla-get-activedocument (vlax-get-acad-object))))
(if (= (type obj) 'ENAME)(setq obj (vlax-ename->vla-object obj)))
(if (= (type obj) 'VLA-OBJECT)
(if (> (vl-string-search "x64" (getvar "platform")) 0)
(vlax-invoke-method util "GetObjectIdString" obj :vlax-False)
(rtos (vla-get-objectid obj) 2 0)
)
)
) ; defun Get-ObjectIDx64
; nested selection function
(defun get_nen (msg / nen)
(while(not nen)
(princ msg)(princ)
(setq nen(car(nentsel))) ; select 1st block's attributes you want to create a field from
(if (not
(or
(eq (vla-get-ObjectName (vlax-ename->vla-object nen)) "AcDbAttribute")
(eq (vla-get-ObjectName (vlax-ename->vla-object nen)) "AcDbText")
; (eq (cdr(assoc 0 (entget nen)))"ATTRIB")
; (eq (cdr(assoc 0 (entget nen)))"TEXT")
)
)
(progn
(setq nen nil)
(princ"\n...Supported Objects are Attribute / Text...")(princ)
)
(redraw nen 3) ; highlight it
) ; if
) ; while
nen
) ; defun
(if(setq en(get_nen "\nPick Source Attribute / Text to Link...")) ; if picked 1st attibute/text
(progn
(setq txt(vla-get-TextString (vlax-ename->vla-object en))) ; get text string
; (setq txt(cdr(assoc 1 (entget en)))) ; get the text string
(setq txt(strcat "%<\\AcObjProp.16.2 Object (%<\\_ObjId " (Get-ObjectIDx64 en) ">%).TextString>%")) ; create new text string as field
(if(setq en1(get_nen "\nPick Target Attribute / Text...")) ; if picked another attibute/text
(progn
(vla-put-TextString(vlax-ename->vla-object en1) txt) ; replace with new text string as field
(command"_.UpdateField" en1 "") ; update the block attribute
; (redraw en1 4) ; unhighlight it
(redraw en 4) ; unhighlight it
)
) ; if
) ; progn
(alert"No Attributes / Text Selected.")
) ; if
(princ)
) ; defun