I can't think of any immediately but will ask our experts tomorrow.

Hi Capt Ramos
This may be helpful. I shall dig a little deeper for you.
Kind regards Nigel Johnstone

https://skybrary.aero/articles/refuelling-and-defuelling-risks

John and Nigel Thank you guys .

There is no direct regulation or rule against this, as long as it is ensured that the fuel is not contaminated. The AFM/AMM will normally specify the applicable fuel specification standard (e.g. ASTM D1655 − 20d).
Per AMC M.A.301(a) Continuing airworthiness tasks (1)(c) pre-flight inspections must include "a control that consumable fluids, gases etc. uplifted prior to flight are of the correct specification, free from contamination, and correctly recorded." Per CAT.GEN.MPA.105 (a) (12) commanders must ensure these are carried out.

Fuel which has been de-fuelled from other aircraft fuel tank(s) can contain microbiological con-
tamination, that can cause operational problems such as corrosion, fuel quantity indication malfunctions or blocking of the scavenge systems and fuel filters.

Many operators therefore have procedures that require fuel which is loaded on aircraft tanks from other carriers to be considered as from an unknown source (unknown specification). The de-fuelled fuel can then only can be refu-
elled if it is ensured through sampling or additives that the fuel is free from contamination and certified to fulfil the applicable fuel specification standard.
Guidance can be found in ICAO Doc 9977 - Manual on Civil Aviation Jet Fuel Supply and the IATA Guidance Material
for Aviation Turbine Fuels Specifications.

Well done guys, im very blessed to be part of this community, but at the same time im devastated that i should do more reading.

I would probably contact a Part-145 organisation or look in 1321/2014. I know this a commom practice within the Part-145 organisations.

Robert Thank you very much for the information.

Goncalo Thank you very much for the info.