# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/(:61:[0-9]{1,6}[0-9]{4}C[0-9]+,[0-9]{0,2})(NMSC.+)(\r?\n:86:RGT FACT[ .])(\d{5}(?:[. ]\d{5})*)/$1$2$3INV$4/gm;t' <<< ":61:2204210421C1339,57NMSCTOPF2510474511//GBBK031SCT TOPF2510474511
:86:RGT FACT 17133 TANQ BROERS SA/RGT39370 TANQ BROERS SA48 AVENUE D'ABCDE
:61:2204270427C4808,37NMSCTOPF2520477320//GBJ6009SCT TOPF2520477320
:86:RGT FACT 17274.17442.17546 TANQ BROERS SA/RGT39370 TANQ BROERS SA48 AVENUE D'ABCDE
:61:2203290329C5518,16NMSCTOPF2485471711//GBCJ001SCT TOPF2485471711
:86:RGT FACT.16794 16918 17079 TANQ BROERS SA/RGT39370 TANQ BROERS SA48 AVENUE D'ABCDE"
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for SED, please visit: https://www.gnu.org/software/sed/manual/html_node/The-_0022s_0022-Command.html